Given an integer n, count the divisors of n.
A divisor is an integer d with 1≤d≤n that divides n evenly.
For example, if n is 10, the divisors are 1, 2, 5, 10, so the answer is 4. If n is 9973, the number is prime, its only divisors are 1 and 9973, and the answer is 2.