620

620 = 2 x 2 x 5 x 31.

620 is the number of one-sided 7-hexes (or hexagonal polyominoes with 7 cells) (A006535).

620 is the sum of four consecutive primes (A034963): 620 = 149 + 151 + 157 + 163. It is also the sum of eight consecutive primes (A127335): 620 = 61 + 67 + 71 + 73 + 79 + 83 + 89 + 97.

The sum of the first 620 primes is a prime number (A013916).

620 is the sum of twelve positive fifth powers (A003357): 620 = 3⁵ + 3⁵ + 2⁵ + 2⁵ + 2⁵ + 2⁵ + 1⁵ + 1⁵ + 1⁵ + 1⁵ + 1⁵ + 1⁵.

Source: What's Special About This Number?