Given an integer
n has exactly three positive divisors. Otherwise, return
m is a divisor of
n if there exists an integer
k such that
n = k * m.
Input: n = 2 Output: false Explantion: 2 has only two divisors: 1 and 2.
Input: n = 4 Output: true Explantion: 4 has three divisors: 1, 2, and 4.