40 (also written as forty or four ten) is the number that is after thirty-nine and before forty-one.
The prime factors of forty are 2 and 5. (2 * 2 * 2 * 5 = 40)
Forty is also the only number in the English language which is spelt in alphabetical order.
The Bible[change | change source]
In the Judeo-Christian Bible, the number forty has special meaning. The Jews wandered in a desert for forty years, there was a forty-day and forty-night rainstorm, and other instances.