The factors of 4 are 4, 1 and 2. The product of two or more factors of a number is equal to that number. Four, 1 and 2 are factors because 1 x 4 = 4, 4 x 1 = 4 and 2 x 2 = 4.
Any non-prime number's factors can be found by first dividing the number by its smallest prime divisor, a number such as 2, 3, 5 and so on. This yields two factors, the smallest prime divisor and another number. If this second number is not prime, the process continues by finding the smallest prime divisor until the entire list of numbers consists of prime numbers. These are the factors of the original number.