Primes

calculates the prime numbers 1..N, tells you if N is prime etc. Prints tables of primes. Computes the prime just below or above N. calculates the prime numbers 1..N, tells you if N is prime etc. It is useful in computing optimal Hashtable sizes. Java source included.

Factorizer may be used: (1) to get the prime decomposition of all numbers in a range of numbers, (2) to get all factors of a single number or all factors of all numbers in a range, (3) to find only the prime numbers in a range of numbers, (4) to find pairs of prime numbers in a certain range, (5) to count (without displaying) the prime numbers in a range of numbers and (6) to find Fermat and Mersenne primes less than 2,147,483,647.

The Prime Number Spiral (a.k.a. the Ulam Spiral) is formed by marking the prime numbers in a spiral arrangement of the natural numbers. This is software is for exploring the Prime Number Spiral.