You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-[4-[4-bromo-2-(trifluoromethoxy)phenyl]sulfonylpiperazin-1-yl]-N-methyl-N-phenylacetamide by IUPAC nomenclature, provide its molecular formula.
user
C20H21BrF3N3O4S
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