The Largest Prime Number to Date Has Been Discovered, And It's 22 Million Digits Long

Try memorising that.

20 JAN 2016

The year is off to a pretty good start for mathematicians, with news that a computer in Missouri has discovered the highest prime number ever seen by humans.

The newly calculated prime number is 274,207,281– 1, and it comes in at around 22 million digits in length. That makes it almost 5 million digits longer than the previous record-holding prime number, which was discovered three years ago.


Why does that matter? For anyone who frequently hangs out with maths enthusiasts, you'll know that they're pretty into prime numbers. Not only because they're so pure - their defining characteristic is that they're only divisible by themselves and one - but also because they can be used to create all sorts of fascinating patterns, such as the Ulam spiral.

More recently, primes have been used to test the power of computers. 

In reality, there's no such thing as the highest prime number, seeing as there's an infinite amount of them. But the quest to find increasingly big ones remains a big deal - so much so that Curtis Cooper, a mathematician at the University of Central Missouri, won US$100,000 for discovering the previous highest prime back in January 2013.

The new record-breaker is part of a rare group known as Mersenne primes, which means that it can be written as one less than a power of two. There are only 49 known Mersenne primes so far, but mathematicians have honed in on them in their search, as they're easier to find and test than other primes.

This new prime - which can be described as two raised to the power of 74,207,281 minus one - was discovered as part of the Great Internet Mersenne Prime Search, a project that over the past 20 years has connected thousands of computers around the world with the aim of hunting down prime numbers.

"It is both the longest continuously running distributed computing project as well as the one with most unfortunate acronym, GIMPS," writes Alex Bellos for The Guardian.

Turns out that Cooper and his computer at the University of Central Missouri were also behind this latest discovery, which was actually made back in September last year, but due to a computer bug, wasn't noticed until this year. Which is pretty funny, considering the fact that the search for prime number is one of the ways people test computer power.

"While prime numbers are important for cryptography, this prime is too large to currently be of practical value. However, the search itself does have several practical benefits," explains a GIMPS press release.

"Historically, searching for Mersenne primes has been used as a test for computer hardware. Earlier this month, GIMPS's prime95 software and members of a German computing community uncovered a flaw in Intel's latest Skylake CPUs. Prime95 has also discovered hardware problems in many individual's PCs."

This is Cooper's fourth record-breaking prime find, and he's up for a $3,000 prize for this discovery. The next big goal is a $150,000 award, which will be given to whoever finds the first 100-million-digit prime number. Anyone looking for a new hobby?

More From ScienceAlert

The supplement industry is barely regulated and it's endangering actual lives

"Most people don't consider it a medication... and so she didn't tell us."

2 hours ago
ScienceAlert Deal: Here's how to get 2TB of cheap, secure cloud storage
1 day ago
This new class of chemical reaction just turned out to be extremely important

It's a new frontier of chemistry and we're freaking out.

3 hours ago