# Write a python function to find sum of all prime divisors of a given number.
def Sum(N):
    SumOfPrimeDivisors = [0] * (N + 1)
    for i in range(2, N + 1):
        if SumOfPrimeDivisors[i] == 0:
            for j in range(i, N + 1, i):
                SumOfPrimeDivisors[j] += i
    return SumOfPrimeDivisors[N]
