Just 1.
3 is the GCF of 123 and 81. Divided into each, you are left with 41 and 27 respectively. There are no further common factors aside from 1.
81 and 200 have no common prime factors.
The common factors of 15 and 81 are 1 and 3
The factors of 81 are 1, 3, 9, 27 and 81. For them to be common, they need to be compared to another set of factors.
The common factors of 72 and 81 are: 1, 3, and 9
34 and 81 share no common factors aside from 1.
81 and 169 share no common factors aside from 1.
The common factors of 36 and 81 are: 1, 3, and 9
The common factors of 81 and 99 are: 1, 3, 9
The factors of 81 are 1, 3, 9, 27, 81. For them to be common, they need to be compared to another set of factors.
The factors of 81 are 1, 3, 9, 27, 81. For them to be common, they need to be compared to another set of factors.
The common factors of 81 and 108 are: 1, 3, 9, and 27