# prime numbers

Euclid proved there is no biggest prime number. As of 1992, 66 primes with more than
10,000 digits were known, and 4,590 with more than 1,000. The largest
prime found to 2006 is 2^{30,402,457}-1 (which is
9,152,052 digits long in decimal notation).

Some special types of primes are:

## Mersenne primes

Primes of the form 2^{q} − 1. For 2^{q} − 1 to be prime, q
must be prime, but not all numbers of this form are prime. Named for Marin
Mersenne (1588 – 1648), a French monk.
Mersenne primes are the subject of the Great Internet Mersenne Prime Search, with a $100,000 prize for the first to discover a prime with more than
10 million decimal digits. Many participants have used the same software: an algorithm by Richard
Crandall implemented
in machine language by George Woltman, and networking software by Scott Kurowski.
The networking software enables the calculations to be run on a massive
distributed computing operation coordinated by Entropia.com, using otherwise
unused time on tens of thousands of home and office PCs. See www.mersenne.org
for details of new and past discoveries.

## Twin primes

A pair of primes that differ by only 2, such as
“3” and “5”. The largest known twin primes are (242,206,083 ×
2^{38880}) ± 1, found by Indlekofer and Ja'rai in November 1995. Each
has 11,713 digits.

The previous record, found by H.
Dubner, is (1,692,923,232 × 104,020) ± 1. It has
4,030 digits.

## Sophie Germain primes

A pair of primes such that one is twice the
other plus 1, for example "11" and "23". Named for a 19th
century French mathematician.

## resources

A poster of the 2005 record prime is
available from www.perfsci.com. You will need a magnifier to read
the numbers, which are printed in one point type.

C. K. Caldwell maintains a list of known
primes (and a lot of other information on primes!) at http://primes.utm.edu/.

Paulo Ribenboim.

*The Little Book of Bigger Primes. *Second edition.

Springer-Verlag, 2004.

Richard Crandall and Carl Pomerance.

*Prime Numbers. A Computational Perspective.*

Springer-Verlag, 2001.

What's the fastest way of computing whether a given large
number is a prime? A text at the graduate level.

Copyright © 2000-2006 Sizes, Inc. All rights reserved.

Last revised: 14 May 2006.