## Sum of squares of unitary divisors

### Problem 429

Published on Sunday, 26th May 2013, 04:00 am; Solved by 955
A unitary divisor `d` of a number `n` is a divisor of `n` that has the property gcd(`d, n/d`) = 1.

The unitary divisors of 4! = 24 are 1, 3, 8 and 24.

The sum of their squares is 1^{2} + 3^{2} + 8^{2} + 24^{2} = 650.

Let S(`n`) represent the sum of the squares of the unitary divisors of `n`. Thus S(4!)=650.

Find S(100 000 000!) modulo 1 000 000 009.