You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
8-[3-(4-chlorophenyl)phenyl]sulfonyl-3-(triazol-2-yl)-8-azabicyclo[3.2.1]octane is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H21ClN4O2S
assistant