Factorizer is a Windows program to find factors of numbers up to 2,147,483,646 and to find primes, pairs of primes and Palmen colors of numbers. Or in more detail, 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 (e.g. 107 and 109) in a certain range, (5) to count (without displaying) the prime numbers in a range of numbers, (6) to find Fermat and Mersenne primes < 2,147,483,647, and (7) to find the Palmen color of a number or the colors of a range of numbers. In addition a "filter" condition may be set to allow examination of numbers with a constant offset from an arithmetical or a geometrical progression, e.g., just those numbers of the form 7*n - 12 or 10n + 2.