Check Whether a Number Is Prime

Given a non-negative integer n, determine whether it is a prime number.

A prime number is a positive integer greater than 1 that has exactly two distinct positive divisors: 1 and itself.

For example, 2 is prime because its only positive divisors are 1 and 2. The number 9 is not prime because it is divisible by 1, 3, and 9.

Numbers less than or equal to 1 are not prime. Return true if n is prime and false otherwise.

Implement the function isPrime(n) that checks whether the given number is prime.

0 <= n <= 1000000000