Missouri mathematician discovers largest known prime number — and it is 22 million digits long


Dr. Curtis Cooper of the University of Central Missouri has discovered the largest known prime number, at 22 million digits long. It is an entire 5 million digits longer than the previous largest prime.
Prime numbers are numbers that are only divisible by themselves and one, such as two, three, five, and seven. Their discovery is particularly important in the world of computer encryption, where they are used to secure online banking, shopping, and private messaging, BBC reports. However, current encryption is typically hundreds of digits long, not millions; Cooper's discovery is currently too large to be of use.
It is still an exciting find: The Great Internet Mersenne Prime Search, or GIMPS, has found 15 of the largest prime numbers in the past 20 years, and says there could be an infinite number to discover. Mainly primes are found using computers, but they are said to be "discovered" when a person notices and reports it.
Subscribe to The Week
Escape your echo chamber. Get the facts behind the news, plus analysis from multiple perspectives.

Sign up for The Week's Free Newsletters
From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.
From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.
So, what exactly is the number? The world's largest known prime is written 2^74,207,281-1 — in other words, multiply two by itself 74,207,281 times, then subtract one.
Go ahead, do the math.
A free daily email with the biggest news stories of the day – and the best features from TheWeek.com
Jeva Lange was the executive editor at TheWeek.com. She formerly served as The Week's deputy editor and culture critic. She is also a contributor to Screen Slate, and her writing has appeared in The New York Daily News, The Awl, Vice, and Gothamist, among other publications. Jeva lives in New York City. Follow her on Twitter.
-
Rubio says US brokered end to Syria conflict
Speed Read Syria's defense ministry was targeted in Israeli attacks on the capital
-
Trump threatens Russia with 'severe tariffs'
speed read The president also agreed to sell NATO advanced arms for Ukraine
-
IDF blames 'error' for strike on Gaza water line
Speed Read Israeli forces attack Palestinians, including children, collecting water in central Gaza
-
Iran still has enriched uranium, Israeli official says
Speed Read It remains unclear how long it would take Iran to rebuild its nuclear program following US and Israeli attacks
-
Trump U-turns on weapons to Ukraine
Speed Read Unhappy with Putin, Trump decides the US will go back to arming Ukraine against Russia's attacks
-
Ukraine scrambles as Trump cuts weapons deliveries
Speed Read The halting of weapons shipments was driven by Pentagon policy chief Elbridge Colby, a Ukraine funding skeptic
-
IAEA: Iran could enrich uranium 'within months'
Speed Read The chief United Nations nuclear inspector, Rafael Grossi, says Iran could be enriching uranium again soon
-
One year after mass protests, why are Kenyans taking to the streets again?
today's big question More than 60 protesters died during demonstrations in 2024