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# The Largest known prime number

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. The Numbers in the picture represents the first 168 prime numbers, all of which are less than 1000.

Discovery or first study of the prime numbers dates back to 300 BC by ancient Greek mathematician. Unfortunately there were not many studies happened until 17th century when Pierre de Fermat came up with Fermat numbers. Marin Mersenne, a French philosopher and mathematician came up with prime numbers of the form of 2p – 1 known as Mersenne prime.

Way back in 3rd century BC, ancient Greek mathematician stated that there is infinite number of prime numbers. Since then mathematicians have been working on an endeavor to find largest prime number. The largest ever known prime number is a Mersenne prime number 257,885,161 – 1 (a 17,425,170 digit number). Dr. Curtis Copper, a professor of University of Central Missouri discovered this prime number on 25th Jan 2013. The number is so big that the primality proof took 39 days of non-stop computing on one of the university’s computer.

Until 19th century there was not much usage of prime numbers. During world war usage of prime numbers started for data encryption. Some of the modern cryptography algorithm is based on prime numbers.