Just 1.
The GCF of 26 and 51 is 1. The prime factors of 26 are 2 and 13. The prime factors of 51 are 3 and 17. There are no factors, other than 1, which are common to 26 and 51.
The common factors of 21 and 51 are: 1 and 3
The common factors of 51 and 68 are: 1 and 17
The common factors of 51 and 85 are: 1 and 17.
The common factors of 51 and 39 are 1 and 3.
1 and 3 are the common factors of 51 and 15.
51 and 16 share no common factors aside from 1.
The factors of 51 are 1, 3, 17, 51 For them to be common, they need to be compared to another set of factors.
It depends upon the other number(s) with which 51 has common factors, but it will always be one of the factors of 51, namely 1, 3, 17 or 51.
The common factors of 24 and 51 are: 1 and 3
The greatest common factor is 51
The factors of 51 are 1, 3, 17 and 51. For them to be common, they need to be compared to another set of factors.