Check Whether a Number Is Prime

Problem

Given an integer n, write a function that returns True if n is a prime number and False otherwise. A prime number is greater than 1 and has exactly two positive divisors: 1 and itself.

Constraints

• -10^9 <= n <= 10^9
• The function should correctly handle negative numbers, 0, and 1
• Aim for better than O(n) time by limiting divisor checks