> For the complete documentation index, see [llms.txt](https://jaywin.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jaywin.gitbook.io/leetcode/solutions/0507-perfect-number.md). # 0507. 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 ```