The prime factors of fifty are 2 and 5. (2 * 5 * 5 = 50) The factors of 50 are 1, 2, 5, 10, 25, and 50. 5*10=50. 50 is the smallest number that can be written as the sum of two squares in two distinct ways: 50=1+7=5+5. Also, 50 is one-half of 100 or half of a century (a century is 100 years).