You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
5-chloro-N-[4-chloro-3-[(3R)-1-methylpyrrolidin-3-yl]oxyphenyl]naphthalene-1-sulfonamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20Cl2N2O3S
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