You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[5-[(3,4-dichlorophenyl)methylsulfanyl]-1,3,4-thiadiazol-2-yl]-4-piperidin-1-ylsulfonylbenzamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20Cl2N4O3S3
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