Prime numbers are divisible only by themselves and one. Some examples of prime numbers are 2, 3, 5, 7, 11, 13, 17, 19. Although there is an infinite number of prime numbers, the most common ones are quite easy to remember.
Every positive integer other than 1 can be written as a product of prime numbers. For example, 30 = 5 * 3 * 2.
A number can be prime or composite. If it is composite, then it has prime factors like 2, 3, 5, 7. A prime number only has two factors: 1 and itself.
There are some prime number facts that you should know:
1. The first prime number is 2. The only even prime number is also 2.
2. There are an infinite amount of prime numbers, but only a finite number have been found so far.