You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(5-chloro-2-methyl-N-methylsulfonylanilino)-N-[(1S)-1-(4-methoxyphenyl)propyl]acetamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H25ClN2O4S
assistant