## Divisor Square Sum

### Problem 211

Published on Saturday, 4th October 2008, 02:00 am; Solved by 2554; Difficulty rating: 50%For a positive integer `n`, let σ_{2}(`n`) be the sum of the squares of its divisors. For example,

σ

_{2}(10) = 1 + 4 + 25 + 100 = 130.Find the sum of all `n`, 0 < `n` < 64,000,000 such that σ_{2}(`n`) is a perfect square.