9 is not a prime number. It can be divided by 3 as well as 1 and 9. The prime numbers below 20 are: 2, 3, 5, 7, 11, 13, 17, 19. Don't forget: the number 1 is not thought of as a prime number.

The largest prime number is now 16 million digits longer than the previous record found in 2018, thanks to an amateur hunter and his large collection of high-power graphics cards ...