You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3-chlorophenyl)-[4-(4-methyl-6-methylsulfanyl-2-propan-2-ylpyrimidine-5-carbonyl)piperazin-1-yl]methanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H25ClN4O2S
assistant