@fluxom_alt prime numbers didn't really have a use until the internet and encryption came along. they were mostly seen as an interesting but dead-ended facet of maths
some types of encryption on the internet will use a 'public' and 'private' key to encrypt and decrypt information, respectively. the private key will be two prime numbers, usually very large; the public key will be those numbers multiplied together.
primes are used because multiplying them is very, very difficult to reverse
@fluxom_alt thanks its me mercury!!!!!!