Problem 211
Divisor Square Sum

For a positive integer n, let σ2(n) be the sum of the squares of its divisors. For example,

σ2(10) = 1 + 4 + 25 + 100 = 130.

Find the sum of all n, 0 <n < 64,000,000 such that σ2(n) is a perfect square.

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http://projecteuler.net/problem=211