507. 完美数

import math


class Solution:
    def checkPerfectNumber(self, num: int) -> bool:
        ans = 0
        for i in range(1, math.ceil(math.sqrt(num))):
            if num % i == 0:
                ans += i
                if i > 1 and num != i * i:
                    ans += num // i
        return ans == num