31 (number)

31 (thirty-one) is a number. It comes between thirty and thirty-two, and is an odd number.  It is also the 11th prime number, after 2, 3, 5, 7, 11, 13, 17, 19,  23, and 29.

The factors of thirty-one are 1 and 31. 

In Roman Numerals, 31 is written as XXXI.
Category:Integers
Category:Prime numbers