Yes, Prime numbers will not have common denominators. They are only divisible by themselves and one. These apply to the interior finished dimensions; floor the hard ceiling and wall to hard wall. Not treatment or furniture.
Now when you are checking available rooms with a mode calc, bear in mind that you have limitations. Make the best of them. Oftentimes it is BETTER to have a larger room with less than perfect modal spread, than to have a smaller room with a better distribution.
If you would like to share your room dimensions here, I would be happy to share and explain for everyone here.