The only number that is always a factor is 1. This is based on my assumption that there are no decimals in your answer.
Yes.
1 and 2
Yes.
No, always odd.
No.
even numbers
Because any number times one equals the original number. Therefore, one and the number itself will always be a factor pair of any given number.
The GCF will always be a positive number.
No, the GCF of 6 and 7 is 1.
No, always odd.
The answer is "1".