N21AN is taken. It's currently assigned to a 1976 Cessna T210L registered in Wendell, NC.
See the full aircraft record →A tail number only frees up if the owner deregisters the aircraft or moves it to a different N-number — and even then the FAA holds it before releasing it to the public.
N21AN has been worn before. Past registrations from FAA deregistration records:
Tails one nudge away from N21AN that aren't assigned or reserved: