[pdpi]

Prime numbers are one of the distinguishing features of number theory, which means they also show up all over the place in anything related to discrete mathematics, which in turn means they show up all over the place in computer science.

Any maths-y field of study that has the concept of decomposition also has the concept of primality, usually in a way that relates to primality in the natural numbers. This means anything we learn about prime numbers also extends to those other fields of study.