Are all numbers prime numbers

Answer 1

No. A Prime number is a number that can only be divided by itself and 1. The first prime number is 2 - which is also the only even prime number. The prime numbers from 1 - 20 are: 2 and 3 and 5 and 7 and 11 and 13 and 17 and 19

Answer 2

Most certainly not.

A prime is a number that has exactly two divisors: 1 and itself.

Example:

2 is a prime. 4 is not; its divisors are: 1, 2 and 4.

Answer 3

They have 2 factors, 1 and itself: 2 is prime, because its factors are - 1,2 3- 1,3 5- 1,5 7- 1,7