Prime Number Calculators
Factor any number into primes !
Prime factorization
One definition of a prime number is: any positive number that has only two positive integer factors, itself and 1. The prime factorization of a number is the product of prime factors that make up that number.
More than 2300 years ago Euclid proved that the number of primes is infinite.
Before the age of computers many mathematicians formed tables of primes. The most widely distributed was D. N. Lehmer's table of primes to 10,006,721. By far the most amazing was a table by Kulik completed in 1867. This table listed the smallest factors of integers (hence all the primes) up to 100,330,200!

1867
The most amazing was a table by Kulik. This table listed the smallest factors of integers (hence all the primes) up to 100,330,200! 
1914
The most widely distributed was D. N. Lehmer's table of primes to 10,006,721. 
1994
Deléglise and Rivat improved the technique once again to find the values for pi(10^{17}>) and pi(10^{18}). 
1867
By far the most amazing was a table by Kulik completed in 1867. This table listed the smallest factors of integers (hence all the primes) up to 100,330,200! 
2004
Xavier Gourdon's distributed computing project determined pi(4*10^{22}) 
2012
The value given for pi(10^{24}) was found by J. Buethe, J. Franke, A. Jost, T. Kleinjung. Similar to the one described by Lagarias and Odlyzko, but uses the Weil explicit formula instead of complex curve integrals. 10^{24} Verified unconditionally by D. J. Platt 2012