# 0507. Perfect Number

https://leetcode.com/problems/perfect-number

## Description

A [**perfect number**](https://en.wikipedia.org/wiki/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`

## ac

```java
```
