Any trademark problem with this domain?

I am thinking of using the domain w w w . not(some number or letter).com

Does this domain has any problem? like trademark or anyother issues?

No it does not, as long as you don't offer anything similar to that brand.. Lets say there's a company with a name Nestle, and I register nestle224, that sounds ok and I can even register my company on that name but make sure you do not exploit their product, in that case they will be able to sue you.