Create a function that returns true if a number is prime, and false otherwise. A prime number is any positive integer that is evenly divisible by only two divisors: 1 and itself.

The first ten prime numbers are:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29

Examples

is_prime(31) ➞ true

is_prime(18) ➞ false

is_prime(11) ➞ true

Notes

• A prime number has no other factors except 1 and itself.
• If a number is odd it is not divisible by an even number.
• 1 is not considered a prime number.