Prime Power

In mathematics, a prime power is a positive integer power of a prime number. For example: 5=51, 9=32 and 16=24 are prime powers, while 6=2×3, 15=3×5 and 36=62=22×32 are not. The twenty smallest prime powers are:

2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 31, 32, 37, 41, ... (sequence A000961 in OEIS)

The prime powers are those positive integers that are divisible by just one prime number; prime powers and related concepts are also called primary numbers, as in the primary decomposition.