You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[3-(2-ethoxyethyl)-6-methylsulfonyl-1,3-benzothiazol-2-ylidene]-3-ethylsulfanylbenzamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H24N2O4S3
assistant