You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-[[3-chloro-4-[(3,4-dichlorophenyl)methoxy]-5-methoxyphenyl]methylidene]-1,3-dimethyl-2-sulfanylidene-1,3-diazinane-4,6-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H17Cl3N2O4S
assistant