You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 7,7-dimethyl-1-[[4-(2-oxo-2-piperidin-1-ylethyl)piperazin-1-yl]sulfonylmethyl]bicyclo[2.2.1]heptan-2-one by IUPAC nomenclature, provide its molecular formula.
user
C21H35N3O4S
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