20,000
Appearance
| ||||
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Cardinal | twenty thousand | |||
Ordinal | 20000th (twenty thousandth) | |||
Factorization | 25 × 54 | |||
Greek numeral | ||||
Roman numeral | XX | |||
Binary | 1001110001000002 | |||
Ternary | 10001022023 | |||
Senary | 2323326 | |||
Octal | 470408 | |||
Duodecimal | B6A812 | |||
Hexadecimal | 4E2016 | |||
Armenian | Ֆ |
20,000 (twenty thousand) is the natural number that comes after 19,999 and before 20,001.
20,000 is a round number, and is also in the title of Jules Verne's 1870 novel Twenty Thousand Leagues Under the Seas.[relevant?]
Selected numbers in the range 20001–29999
20001 to 20999
- 20002 = number of surface-points of a tetrahedron with edge-length 100[1]
- 20067 = The smallest number with no entry in the Online Encyclopedia of Integer Sequences (OEIS)[2]
- 20100 = sum of the first 200 natural numbers (hence a triangular number)
- 20160 = highly composite number;[3] the smallest order belonging to two non-isomorphic simple groups: the alternating group A8 and the Chevalley group A2(4)
- 20161 = the largest integer that cannot be expressed as a sum of two abundant numbers
- 20230 = pentagonal pyramidal number[4]
- 20412 = Leyland number:[5] 93 + 39
- 20540 = square pyramidal number[6]
- 20569 = tetranacci number[7]
- 20593 = unique prime in base 12
- 20597 = k such that the sum of the squares of the first k primes is divisible by k.[8]
- 20736 = 1442 = 124, 1000012, palindromic in base 15 (622615)
- 20793 = little Schroeder number
- 20871 = The number of weeks in exactly 400 years in the Gregorian calendar
- 20903 = first prime of form 120k + 23 that is not a full reptend prime
21000 to 21999
- 21025 = 1452, palindromic in base 12 (1020112)
- 21147 = Bell number[9]
- 21181 = the least of five remaining Seventeen or Bust numbers in the Sierpiński problem
- 21209 = number of reduced trees with 23 nodes[10]
- 21637 = number of partitions of 37[11]
- 21856 = octahedral number[12]
- 21943 = Friedman prime
- 21952 = 283
- 21978 = reverses when multiplied by 4: 4 × 21978 = 87912
22000 to 22999
- 22050 = pentagonal pyramidal number[4]
- 22140 = square pyramidal number[6]
- 22222 = repdigit, Kaprekar number:[13] 222222 = 493817284, 4938 + 17284 = 22222
- 22447 = cuban prime[14]
- 22527 = Woodall number: 11 × 211 − 1[15]
- 22621 = repunit prime in base 12
- 22699 = one of five remaining Seventeen or Bust numbers in the Sierpiński problem
23000 to 23999
- 23000 = number of primes .[16]
- 23401 = Leyland number:[5] 65 + 56
- 23409 = 1532, sum of the cubes of the first 17 positive integers
- 23497 = cuban prime[14]
- 23821 = square pyramidal number[6]
- 23833 = Padovan prime
- 23969 = octahedral number[12]
- 23976 = pentagonal pyramidal number[4]
24000 to 24999
- 24000 = number of primitive polynomials of degree 20 over GF(2)[17]
- 24211 = Zeisel number[18]
- 24336 = 1562, palindromic in base 5: 12343215
- 24389 = 293
- 24571 = cuban prime[14]
- 24631 = Wedderburn–Etherington prime[19]
- 24649 = 1572, palindromic in base 12: 1232112
- 24737 = one of five remaining Seventeen or Bust numbers in the Sierpinski problem
- 24742 = number of signed trees with 10 nodes[20]
25000 to 25999
- 25011 = the smallest composite number, ending in 1, 3, 7, or 9, that in base 10 remains composite after any insertion of a digit
- 25085 = Zeisel number[18]
- 25117 = cuban prime[14]
- 25200 = 224th triangular number, highly composite number, smallest number with exactly 90 factors[3]
- 25205 = largest number whose factorial is less than 10100000
- 25482 = number of 21-bead necklaces (turning over is allowed) where complements are equivalent[21]
- 25585 = square pyramidal number[6]
- 25724 = Fine number[22]
- 25920 = smallest number with 70 factors
26000 to 26999
- 26015 = number of partitions of 38[23]
- 26214 = octahedral number[12]
- 26227 = cuban prime[14]
- 26272 = number of 20-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed[24]
- 26861 = smallest number for which there are more primes of the form 4k + 1 than of the form 4k + 3 up to the number, against Chebyshev's bias
- 26896 = 1642, palindromic in base 9: 408049
27000 to 27999
- 27000 = 303
- 27405 = heptagonal number,[25] hexadecagonal number,[26] 48-gonal number, 80-gonal number, smallest integer that is polygonal in exactly 10 ways.[27]
- 27434 = square pyramidal number[6]
- 27559 = Zeisel number[18]
- 27594 = number of primitive polynomials of degree 19 over GF(2)[17]
- 27648 = 11 × 22 × 33 × 44
- 27653 = Friedman prime
- 27720 = highly composite number;[3] smallest number divisible by the numbers from 1 to 12 (there is no smaller number divisible by the numbers from 1 to 11 since any number divisible by 3 and 4 must be divisible by 12)
- 27846 = harmonic divisor number[28]
- 27889 = 1672
28000 to 28999
- 28158 = pentagonal pyramidal number[4]
- 28374 = smallest integer to start a run of six consecutive integers with the same number of divisors
- 28393 = unique prime in base 13
- 28547 = Friedman prime
- 28559 = nice Friedman prime
- 28561 = 1692 = 134 = 1192 + 1202, number that is simultaneously a square number and a centered square number, palindromic in base 12: 1464112
- 28595 = octahedral number[12]
- 28657 = Fibonacci prime,[29] Markov prime[30]
- 28900 = 1702, palindromic in base 13: 1020113
29000 to 29999
- 29241 = 1712, sum of the cubes of the first 18 positive integers
- 29341 = Carmichael number[31]
- 29370 = square pyramidal number[6]
- 29527 = Friedman prime
- 29531 = Friedman prime
- 29601 = number of planar partitions of 18[32]
- 29791 = 313
Primes
There are 983 prime numbers between 20000 and 30000.
References
- ^ Sloane, N. J. A. (ed.). "Sequence A005893 (Number of points on surface of tetrahedron)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Bischoff, Manon (March 3, 2023). "The Most Boring Number in the World Is ..." Scientific American. Springer Nature.
- ^ a b c Sloane, N. J. A. (ed.). "Sequence A002182 (Highly composite numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ a b c d Sloane, N. J. A. (ed.). "Sequence A002411 (Pentagonal pyramidal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ a b Sloane, N. J. A. (ed.). "Sequence A076980 (Leyland numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ a b c d e f Sloane, N. J. A. (ed.). "Sequence A000330 (Square pyramidal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000078 (Tetranacci numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A111441 (Numbers k such that the sum of the squares of the first k primes is divisible by k)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-06-02.
- ^ Sloane, N. J. A. (ed.). "Sequence A000110 (Bell or exponential numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000014 (Number of series-reduced trees with n nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000041 (a(n) is the number of partitions of n (the partition numbers))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ a b c d Sloane, N. J. A. (ed.). "Sequence A005900 (Octahedral numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A006886 (Kaprekar numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ a b c d e Sloane, N. J. A. (ed.). "Sequence A002407 (Cuban primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A003261 (Woodall numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A007053 (Number of primes [greater than or equal to] 2^n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-06-02.
- ^ a b Sloane, N. J. A. (ed.). "Sequence A011260 (Number of primitive polynomials of degree n over GF(2))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ a b c Sloane, N. J. A. (ed.). "Sequence A051015 (Zeisel numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A001190 (Wedderburn-Etherington numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000060 (Number of signed trees with n nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000011 (Number of n-bead necklaces (turning over is allowed) where complements are equivalent)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000957 (Fine's sequence (or Fine numbers): number of relations of valence > 0 on an n-set; also number of ordered rooted trees with n edges having root of even degree)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-06-01.
- ^ Sloane, N. J. A. (ed.). "Sequence A000041 (a(n) is the number of partitions of n (the partition numbers))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000013 (Definition (1): Number of n-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A000566 (Heptagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A051868 (Hexadecagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A063778 (a(n) = the least integer that is polygonal in exactly n ways.)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ "Sloane's A001599 : Harmonic or Ore numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
- ^ "Sloane's A000045 : Fibonacci numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
- ^ "Sloane's A002559 : Markoff (or Markov) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
- ^ "Sloane's A002997 : Carmichael numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
- ^ Sloane, N. J. A. (ed.). "Sequence A000219 (Number of planar partitions (or plane partitions) of n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.