1952\. Three Divisors

Easy

Given an integer `n`, return `true` _if_ `n` _has **exactly three positive divisors**. Otherwise, return_ `false`.

An integer `m` is a **divisor** of `n` if there exists an integer `k` such that `n = k * m`.

**Example 1:**

**Input:** n = 2

**Output:** false

**Explantion:** 2 has only two divisors: 1 and 2.

**Example 2:**

**Input:** n = 4

**Output:** true

**Explantion:** 4 has three divisors: 1, 2, and 4.

**Constraints:**

*   <code>1 <= n <= 10<sup>4</sup></code>
