Leetcode 507. Perfect Number

class Solution {
public:
    bool checkPerfectNumber(int num) {
        if(num == 1) {
            return false;
        }
        int sum = 1;
        int root = sqrt(num) + 1;
        for(int i = 2; i < root; i++) {
            if(num % i == 0) {
                sum += i;
                if(i * i != num) {
                    sum += num / i;
                }
            }
        }
        return sum == num;
    }
};