5

is the integer between and.

Math features

 * 5 is an odd number.
 * 5 is the first odd number to be a non-Mersenne number, but 5 is a Fermat prime, equal to 22 + 1.
 * 5 is one of the 3|three divisors of 10: 1, 2 and 5 are the divisors of 10.
 * 5 is a square pyramidal number, equal to $$\sum_{n=0}^2n^2$$, which is 22 + 12 = 5.