The only whole number that can do that is ' 1 '.
34
3 goes into 36 and 63 evenly.
It is: 1
1, 2, 17, 34
1 and 7.
It is: 7 and 1
One.
1, 3, 7, 9, 21, 63.
1, 3, 7, 9, 21, 63.
1, 3, 9.
4 goes into 63, 15 times evenly with a remainder of 3
The greatest common factor is 63