What are the common factors for 36 336 and 504?

The factors of 336 are:

1, 2, 3, 4, 6, 7, 8, 12, 14, 16, 21, 24, 28, 42, 48, 56, 84, 112, 168, 336

The factors of 504 are:

1, 2, 3, 4, 6, 7, 8, 9, 12, 14, 18, 21, 24, 28, 36, 42, 56, 63, 72, 84, 126, 168, 252, 504

The common factors are:

1, 2, 3, 4, 6, 12