40000

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. Additionally, it's a 390-gonal, 4077-gonal, and 13586-gonal number. 40804 = palindromic square