You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-(1-benzothiophen-3-ylmethyl)-3-(2,3-dihydro-1,4-benzodioxin-6-yl)-N-methylpropanamide by IUPAC nomenclature, provide its molecular formula.
user
C21H21NO3S
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