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Revision as of 14:02, 23 January 2016

As of January 2016, the largest known prime number is 274,207,281 − 1, a number with 22,338,618 digits. It was found in 2016 by the Great Internet Mersenne Prime Search (GIMPS).

Plot of the number of digits in largest known prime by year, since the electronic computer. Note that the vertical scale is logarithmic. The red line is the exponential curve of best fit: y = exp(0.187394 t - 360.527), where t is in years.

Euclid proved that there is no largest prime number, so many mathematicians and hobbyists continue to search for large prime numbers.

Many of the largest known primes are Mersenne primes. As of January 2016 the eleven largest known primes are Mersenne primes, while the twelfth is the largest known non-Mersenne prime.[1] The last 16 record primes were Mersenne primes.[2][3]

The fast Fourier transform implementation of the Lucas–Lehmer primality test for Mersenne numbers is fast compared to other known primality tests for other kinds of numbers.

The current record

The record is currently held by 274,207,281 − 1 with 22,338,618 digits, discovered by the GIMPS in 2016.[4] The value of it is:

300376418084606182052986098359166050056875863030301484843941693345547723219067994296893655300772688320448214882399426831
... (22,338,378 digits omitted) ...
717774014762912462113646879425801445107393100212927181629335931494239018213879217671164956287190498687010073391086436351

The first and last 120 digits are shown above.

Prizes

The Great Internet Mersenne Prime Search (GIMPS) currently offers a US $3000 research discovery award for participants who download and run their free software and whose computer discovers a new Mersenne prime having fewer than 100 million digits.

There are several prizes offered by the Electronic Frontier Foundation for record primes.[5] GIMPS is also coordinating its long-range search efforts for primes of 100 million digits and larger and will split the Electronic Frontier Foundation's US $150,000 prize with a winning participant.

The record passed one million digits in 1999, earning a $50,000 prize.[6] In 2008 the record passed ten million digits, earning a $100,000 prize and a Cooperative Computing Award from the Electronic Frontier Foundation.[5] Time called it the 29th top invention of 2008.[7] Additional prizes are being offered for the first prime number found with at least one hundred million digits and the first with at least one billion digits.[5] Both the $50,000 and the $100,000 prizes were won by participation in GIMPS.

History

The following table lists the progression of the largest known prime number in ascending order.[2] Here Mn= 2n − 1 is the Mersenne number with exponent n. The longest record-holder known was M19 = 524,287, which was the largest known prime for 144 years. No records are known before 1456.

Number # digits Year found Notes
(For larger Mersenne primes, see Mersenne prime)
M13 8,191 4 1456 Anonymous discovery
M17 131,071 6 1460 Anonymous discovery
M19 524,287 6 1588 Found by Pietro Cataldi
(232+1)/641 6,700,417 7 1732 Found by Leonhard Euler
M31 2,147,483,647 10 1772 Found by Leonhard Euler
(264+1)/274177 67,280,421,310,721 14 1855 Found by Thomas Clausen
M127 170,141,183,460,469,231,731,687,303,715,884,105,727 39 1876 Found by Édouard Lucas
(2148+1)/17 20,988,936,657,440,586,486,151,264,256,610,222,593,863,921 44 1951 Found by Aimé Ferrier; the largest record not set by computer.
180×(M127)2+1 79 1951 Using Cambridge's EDSAC computer
M521 157 1952
M607 183 1952
M1279 386 1952
M2203 664 1952
M2281 687 1952
M3217 969 1957
M4423 1,332 1961
M9689 2,917 1963
M9941 2,993 1963
M11213 3,376 1963
M19937 6,002 1971
M21701 6,533 1978
M23209 6,987 1979
M44497 13,395 1979
M86243 25,962 1982
M132049 39,751 1983
M216091 65,050 1985
391581×2216193−1 65,087 1989
M756839 227,832 1992
M859433 258,716 1994
M1257787 378,632 1996
M1398269 420,921 1996
M2976221 895,932 1997
M3021377 909,526 1998
M6972593 2,098,960 1999
M13466917 4,053,946 2001
M20996011 6,320,430 2003
M24036583 7,235,733 2004
M25964951 7,816,230 2005
M30402457 9,152,052 2005
M32582657 9,808,358 2006
M43112609 12,978,189 2008
M57885161 17,425,170 2013
M74207281 22,338,618 2016

The ten largest known prime numbers

Rank Prime number Found by Found date Number of digits Reference
1st 274,207,281 − 1 GIMPS 2016 January 7 22,338,618 [8]
2nd 257,885,161 − 1 GIMPS 2013 January 25 17,425,170 [8]
3rd 243,112,609 − 1 GIMPS 2008 August 23 12,978,189 [8]
4th 242,643,801 − 1 GIMPS 2009 April 12 12,837,064 [9]
5th 237,156,667 − 1 GIMPS 2008 September 6 11,185,272 [9]
6th 232,582,657 − 1 GIMPS 2006 September 4 9,808,358 [9]
7th 230,402,457 − 1 GIMPS 2005 December 15 9,152,052 [10]
8th 225,964,951 − 1 GIMPS 2005 February 18 7,816,230 [10]
9th 224,036,583 − 1 GIMPS 2004 May 15 7,235,733 [10]
10th 220,996,011 − 1 GIMPS 2003 November 17 6,320,430 [10]

GIMPS found the thirteen latest records on ordinary computers operated by participants around the world (and found one prime that was not a record).

The largest known prime that is not a Mersenne prime is 19249 × 213018586 + 1, found by Seventeen or Bust.[11] This is currently the twelfth largest known prime.

See also

References

  1. ^ Caldwell, Chris. "The largest known primes - Database Search Output". Prime Pages. Retrieved January 20, 2016.
  2. ^ a b Caldwell, Chris. "The Largest Known Prime by Year: A Brief History". Prime Pages. Retrieved January 20, 2016.
  3. ^ The last non-Mersenne to be the largest known prime, was 391,581 ⋅ 2216,193 − 1; see also The Largest Known Prime by Year: A Brief History by Caldwell.
  4. ^ "Mersenne Prime Number discovery - 274207281-1". Great Internet Mersenne Prime Search. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  5. ^ a b c "Record 12-Million-Digit Prime Number Nets $100,000 Prize". Electronic Frontier Foundation. Electronic Frontier Foundation. October 14, 2009. Retrieved November 26, 2011.
  6. ^ Electronic Frontier Foundation, Big Prime Nets Big Prize.
  7. ^ "Best Inventions of 2008 - 29. The 46th Mersenne Prime". Time. Time Inc. October 29, 2008. Retrieved January 17, 2012.
  8. ^ a b c Chris Caldwell, The largest known primes. Retrieved on 2013-02-05.
  9. ^ a b c Landon Curt Noll, Mersenne Prime Digits and Names. Retrieved on 2011-01-03.
  10. ^ a b c d Samuel Yates, Chris Caldwell, The largest known primes. Retrieved on 2014-03-08.
  11. ^ "Press release, 5 May 2007". Seventeen or Bust.