There cannot be a greatest common factor of just one number. To be common there need to be at least two numbers.
The GCF is: 63
The GCF is 21.
The GCF is 9.
The GCF is 63.
The GCF is 9.
The GCF is 7.
The GCF is 1.
The GCF is 9.
The GCF is 63.
The GCF is 63.
The GCF is 3.
The GCF is 1.