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 = 6 Output: true Example 3: Input: num = 496 Output: true Example 4: Input: num = 8128 Output: true Example 5: Input: num = 2 Output: false Constraints: 1 <= num <= 108