ZOJ Problem Set - 2095
Give a natural number n (1 <= n <= 500000), please tell the summation of all its proper divisors.
Definition: A proper divisor of a natural number is the divisor that is strictly less than the number.
e.g. number 20 has 5 proper divisors: 1, 2, 4, 5, 10, and the divisor summation is: 1 + 2 + 4 + 5 + 10 = 22.
An integer stating the number of test cases, and that many lines follow each containing one integer between 1 and 500000.
One integer each line: the divisor summation of the integer given respectively.
Author: Neal Zane
Source: ZOJ Monthly, March 2004