You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[1-[(7-chloro-1,3-benzodioxol-5-yl)methyl]piperidin-3-yl]-3-methylsulfonylpyridine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H21ClN2O4S
assistant