Question 904939
We consider whole numbers greater than 1 and NOT fractions:
1) It is a Composite Number when it can be divided evenly
by numbers other than 1 or itself. 
2) It is a Prime Number when it can't be divided evenly by any number
(except 1 or itself). 
a) Now we can consider "The Fundamental Theorem of Arithmetic", this Theorem states;  "that every integer greater than 1 either is prime itself or is the product of prime numbers, and that, although the order of the primes in the second case is arbitrary, the primes themselves are not"
Therefore there is only one prime factorization of a composite number.
You can find the proof on the Internet.
b) 1 has no prime factors