from math import sqrt

def is_prime(n):
    if not isinstance(n, int):
        return False
    elif n < 2:
        return False

    for i in range(2, int(sqrt(n))+1):
        if n % i == 0:
            return False
    return True

n = int(input())
ans = 0

for i in range(2,round(sqrt(n))+1):
    if is_prime(i):
        t = 2
        while True:
            if n**(1/t) < i:
                break
            else:
                ans += i**t
                t += 1

print(ans)