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 <= 10^8
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