130 is a sphenic number. It is a noncototient since there is no answer to the equation x - φ(x) = 130.

130 is the only integer that is the sum of the squares of its first four divisors, including 1: 12 + 22 + 52 + 102 = 130.

130 is the largest number that cannot be written as the sum of four hexagonal numbers.

How wonderful!

Enjoy these fantastic submissions - and as I said last week, and before that, still sooooo much to catch up on... Maybe in a few months there will be literally nothing to upload after an update...