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New largest prime number found in Missouri

Computer security experts use really big prime numbers to encrypt valuable data and safeguard digital infrastructure.
By Brooks Hays   |   Jan. 20, 2016 at 9:58 AM

WARRENSBURG, Mo., Jan. 20 (UPI) -- There's a new largest prime number in town, and at 22 million digits, it's bigger than the last by 5 million digits.

But no one's feelings are hurt too badly, because the discoverer of the new number also discovered the last one. Also, the discoverer is a computer.

The number is 2^74,207,281-1. To get the unabridged version, simply multiply two by itself 74,207,281 times and then subtract one. When stretched in full, the number is more than 22 million digits long.

All prime numbers are found this way -- by multiplying two by two so many times and taking away one -- but the method doesn't always turn out prime results.

Although a computer does all the number crunching, a new prime number is only acknowledged when a human recognizes a prime output. The new number has been credited to Dr. Curtis Cooper at the University of Central Missouri.

According to the New Scientist, the new number was actually discovered last year on Sept. 17. But a glitch in the software caused an email alert to go unsent. Cooper discovered the result only recently while logging in to the program to do some routine maintenance.

The search and discovery was part of an ongoing effort to find bigger and bigger prime numbers called the Great Internet Mersenne Prime Search, or GIMPS.

Computer security experts use really big prime numbers to encrypt valuable data and safeguard digital infrastructure. Finding new prime numbers diversifies their protective arsenal.

But in a statement, GIMPS officials said the latest discovery will be of little use.

"While prime numbers are important for cryptography, this prime is too large to currently be of practical value," they wrote.

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