40,000

"40k" redirects here. For the tabletop game, see Warhammer 40,000. For the isotope ⁴⁰K, see Potassium-40.

40,000 (forty thousand) is the natural number that comes after 39,999 and before 40,001. It is the square of 200.

← 39999 40000 40001 →
List of numbers Integers ← 0 10k 20k 30k 40k 50k 60k 70k 80k 90k →
Cardinal	forty thousand
Ordinal	40000th (forty thousandth)
Factorization	2^6 × 5^4
Divisors	35 total
Greek numeral	${\displaystyle {\stackrel {\delta }{\mathrm {M} }}}$
Roman numeral	XL
Binary	10011100010000002
Ternary	20002121113
Senary	5051046
Octal	1161008
Duodecimal	1B19412
Hexadecimal	9C4016

Selected numbers in the range 40001–49999

40001 to 40999

• 40320 = smallest factorial (8!) that is not a highly composite number
• 40425 = square pyramidal number
• 40585 = largest factorion^[1]
• 40678 = pentagonal pyramidal number
• 40755 = Triangular number, Pentagonal number, Hexagonal number, 390-gonal, 4077-gonal, and 13586-gonal number.^[2][3][4]
• 40804 = palindromic square

41000 to 41999

• 41041 = Carmichael number^[5]
• 41472 = 3-smooth number, number of reduced trees with 24 nodes^[6]
• 41586 = Large Schröder number
• 41616 = triangular square number^[7]
• 41835 = Motzkin number^[8]
• 41841 = 1/41841 = 0.0000239 is a repeating decimal with period 7

42000 to 42999

• 42680 = octahedral number^[9]
• 42875 = 35³
• 42925 = square pyramidal number

43000 to 43999

• 43261 = Markov number^[10]
• 43380 = number of nets of a dodecahedron
• 43390 = number of primes ${\displaystyle \leq 2^{19}}$ .^[11]
• 43560 = pentagonal pyramidal number
• 43691 = Wagstaff prime^[12]
• 43777 = smallest member of a prime sextuplet

44000 to 44999

• 44044 = palindrome of 79 after 6 iterations of the "reverse and add" iterative process^[13]
• 44100 = sum of the cubes of the first 20 positive integers 44,100 Hz is a common sampling frequency in digital audio (and is the standard for compact discs).
• 44444 = repdigit
• 44583 = number of partitions of 41^[14]
• 44721 = smallest positive integer such that the expression 1/n − 1/n + 2 ≤ 10⁻⁹
• 44724 = maximum number of days in which a human being has been verified to live (Jeanne Calment).^[15]
• 44944 = palindromic square

45000 to 45999

• 45360 = highly composite number;^[16] smallest number with exactly 100 factors (including one and itself)

46000 to 46999

• 46080 = double factorial of 12
• 46233 = sum of the first eight factorials
• 46249 = 2nd number that can be written as ${\displaystyle a^{2}+b!}$  in 3 ways^[17]
• 46368 = Fibonacci number^[18]
• 46656 = 36³, 6⁶, 3-smooth number
• 46657 = Carmichael number^[5]

47000 to 47999

• 47058 = primary pseudoperfect number^[19]
• 47160 = 10-th derivative of x^x at x=1^[20]
• 47321/33461 ≈ √2

48000 to 48999

• 48629 = number of trees with 17 unlabeled nodes^[21]
• 48734 = number of 22-bead necklaces (turning over is allowed) where complements are equivalent^[22]

49000 to 49999

• 49151 = Woodall number^[23]
• 49152 = 3-smooth number
• 49726 = pentagonal pyramidal number
• 49940 = number of 21-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed^[24]

Primes

There are 930 prime numbers between 40000 and 50000.

References

1. "Sloane's A014080 : Factorions". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
2. Sloane, N. J. A. (ed.). "Sequence A000217 (Triangular numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
3. Sloane, N. J. A. (ed.). "Sequence A000326 (Pentagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
4. Sloane, N. J. A. (ed.). "Sequence A000384 (Hexagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
5. "Sloane's A002997 : Carmichael numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
6. Sloane, N. J. A. (ed.). "Sequence A000014 (Number of series-reduced trees with n nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
7. "Sloane's A001110 : Square triangular numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
8. "Sloane's A001006 : Motzkin numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
9. "Sloane's A005900 : Octahedral numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
10. "Sloane's A002559 : Markoff (or Markov) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-15.
11. Sloane, N. J. A. (ed.). "Sequence A007053 (Number of primes <= 2^n)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
12. Sloane, N. J. A. (ed.). "Sequence A000979 (Wagstaff primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
13. "Reversal-Addition Palindrome Test on 79".
14. 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.
15. Amzallag, William. "The Promise of Immortality". books/google.com. Varegus Publishing. Retrieved September 22, 2016.
16. Sloane, N. J. A. (ed.). "Sequence A002182 (Highly composite numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
17. Sloane, N. J. A. (ed.). "Sequence A359013 (Numbers k that can be written as the sum of a perfect square and a factorial in exactly 3 distinct ways)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
18. Sloane, N. J. A. (ed.). "Sequence A000045 (Fibonacci numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
19. Sloane, N. J. A. (ed.). "Sequence A054377 (Primary pseudoperfect numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
20. Sloane, N. J. A. (ed.). "Sequence A005727 (n-th derivative of x^x at x=1. Also called Lehmer-Comtet numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
21. Sloane, N. J. A. (ed.). "Sequence A000055 (Number of trees with n unlabeled nodes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
22. 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.
23. Sloane, N. J. A. (ed.). "Sequence A003261 (Woodall numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
24. 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.