The 6 factors of 45 are 1, 3, 5, 9, 15, & 45.
The factor pairs of 45 are 1 x 45, 3 x 15, & 5 x 9.
The proper factors of 45 are 1, 3, 5, 9, & 15 or if the definition you are using excludes 1, they are 3, 5, 9, & 15.
The prime factors of 45 are 3, 3, & 5.
There is repetition of these factors, therefore if the prime factors are being listed instead of the prime factorization, usually only the distinct prime factors are listed.
The 2 distinct prime factors of 45 are 3 & 5.
The prime factorizations of 45 are 3 x 3 x 5 or, in index form 32 x 5.
There cannot be common factors, a least common multiple of a single number or a greatest common factor because "common" refers to factors or multiples that 2 or more numbers have in common.