There’s a new biggest known prime number in the universe.
It’s called M77232917, and it looks like this:
Despite being a ridiculously huge number (just that text file, which readers can download here, takes up more than 23 megabytes of space on a computer), M77232917 can’t be divided up without using fractions. It won’t break into integers no matter what other factors, large or small, someone divides it by. Its only factors are itself and the number 1. That’s what makes it prime.