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

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 40678 = pentagonal pyramidal number 40755 = the smallest number >1 to be a Triangular number, Pentagonal number, and a Hexagonal number. 40804 = palindromic square

41000 to 41999 41041 = Carmichael number 41472 = 3-smooth number, number of reduced trees with 24 nodes 41586 = Large Schröder number 41616 = triangular square number 41835 = Motzkin number

42000 to 42999 42680 = octahedral number 42925 = square pyramidal number

43000 to 43999 43261 = Markov number 43380 = number of nets of a dodecahedron 43390 = number of primes . 43560 = pentagonal pyramidal number 43691 = Wagstaff prime 43777 = smallest member of a prime sextuplet

44000 to 44999 44044 = palindrome of 79 after 6 iterations of the "reverse and add" iterative process 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). 44583 = number of partitions of 41 44721 = smallest positive integer such that the expression − ≤ 10−9 44724 = maximum number of days in which a human being has been verified to live (Jeanne Calment). 44944 = palindromic square

45000 to 45999

45360 = 26th highly composite number; 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 in 3 ways 46368 = Fibonacci number 46656 = 216 = 36 = 66, 3-smooth number 46657 = Carmichael number 46972 = number of prime knots with 14 crossings

47000 to 47999 47058 = primary pseudoperfect number 47160 = 10-th derivative of xx at x=1 47321/33461 ≈ √2

48000 to 48999 48629 = number of trees with 17 unlabeled nodes 48734 = number of 22-bead necklaces (turning over is allowed) where complements are equivalent

49000 to 49999 49151 = Woodall number 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

Primes There are 930 prime numbers between 40000 and 50000.

References