A prime with 
digits. As of 1990, more than 1400 were known (Ribenboim 1990). By 1995, more than 
were known, and many tens of thousands are known today. The largest currently known is the Mersenne prime 
,
digits (Weisstein 2004).
Gigantic Prime, Large Number, Mersenne Prime, Prime Number, Probable Prime
Caldwell, C. "The Ten Largest Known Primes." http://www.utm.edu/research/primes/largest.html#largest.
Lifchitz, H. and Lifchitz, R. "PRP Records: Probable Primes Top 5000." http://www.primenumbers.net/prptop/prptop.php.
Morain, F. "Elliptic Curves, Primality Proving and Some Titanic Primes." Astérique 198-200, 245-251, 1992.
Ribenboim, P. The Little Book of Big Primes. Berlin: Springer-Verlag, p. 97, 1990.
Weisstein, E. W. "40th Mersenne Announced." MathWorld Headline News, Dec. 2, 2003. http://mathworld.wolfram.com/news/2003-12-02/mersenne/.
Yates, S. "Titanic Primes." J. Recr. Math. 16, 250-262, 1983-84.
Yates, S. "Sinkers of the Titanics." J. Recr. Math. 17, 268-274, 1984-85.