We like to do the numbers on Marketplace. and this week, a new number has arrived: M74207281

If you think that name sounds long, be warned: it is an extreme abbreviation. The largest known prime number, discovered this week by University of Central Missouri computer science professor Curtis Cooper, actually has more than 22 million digits.

When was the last time you talked about prime numbers? High School?  Reminder: it’s when a number only has multiples of one and itself.  Examples include two, five, seven, et cetera. The higher you get, the harder it is to find primes. 

So why are they important? Curtis Cooper tells us: “They’re used routinely for encryption when you do transactions across the internet, making sure the information is encrypted so that nobody can hack in and steal that information.”

Granted, encryption with the new massive prime is a long way away. Most encryption these days uses numbers that are 2 to 300 digits long. 

If you want to discover more primes all by yourself, there’s free software to help — it’s called prime 95.