The factors of 27 are one, three, nine and 27. The factors of a particular number are those numbers that divide evenly into it. One and the number itself are always factors of any given number.
The multiplication facts for 27 are 1 x 27, 27 x 1, 3 x 9 and 9 x 3. Because prime numbers are numbers that have only one and themselves as factors, 27 is not a prime number. Like all integers, however, it can be factored into only prime numbers. Take the factors 9 x 3. Three is a prime number, but nine is not. Factor it further into 3 x 3. The prime factorization of 27 then is 3 x 3 x 3 or 3^3.