Leetcode•Jul 03, 2026
Perfect Number
Hazrat Ali
Leetcode
A perfect number is a positive integer that is equal to the sum of its positive divisors, excluding the number itself. A divisor of an integer x is an integer that can divide x evenly.
Given an integer n, return true if n is a perfect number, otherwise return false.
Example 1:
Input: num = 28 Output: true Explanation: 28 = 1 + 2 + 4 + 7 + 14 1, 2, 4, 7, and 14 are all divisors of 28.
Example 2:
Input: num = 7 Output: false
Solution
/**
* @param {number} num
* @return {boolean}
*/
var checkPerfectNumber = function(num) {
if (num <= 1) return false;
let sum = 1;
for (let i = 2; i * i <= num; i++) {
if (num % i === 0) {
sum += i;
if (i !== num / i) {
sum += num / i;
}
}
}
return sum === num;
};