Many prime factorization algorithms have been devised for determining the prime factors of a given integer, a process known as factorization or prime factorization. Here is a list of prime numbers : 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191. Euclid gives a proof of the Fundamental Theorem of Arithmetic: Every integer can be written as a product of primes in an essentially unique way. He proved a speculation of Albert Girard that every prime number of the form 4 n + 1 can be written in a unique way as the sum of two squares and was able to show how any number could be written as a sum of four squares.
Eratosthenes (275-194 B.C., Greece) devised a ‘sieve’ to discover prime numbers. A sieve is like a strainer that you use to drain spaghetti when it is done cooking.