A prime number has precisely two distinct (different) factors: itself and 1.

The number 1 is not prime. It has only one factor.

1. How many even prime numbers are there?

2. List all the prime numbers between 10 and 20.

3. What is the name for a whole number > 1 that is not prime?

4. List three consecutive prime numbers.

5. Is it true that the sum of two prime numbers is a prime number?