The prime factorization of 68 is 2 x 2 x 17. There is only one set of prime factorials for any number. The set of prime factorials is the set of prime numbers that when multiplied together get the original number.
To find the prime factorials for any number divide the number by the smallest prime possible, then divide the result by the smallest prime, and continue this process until the result is a prime number. The primes that were used to divide and the result are the set of prime factorials. For example 68 divided by 2 is 34. Then 34 divided by 2 is 17. Since 17 is a prime number 2, 2 and 17 are the prime factorials of 68.