You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[2-(4-bromo-2-fluorophenyl)-2-hydroxyacetyl]-N-pyridin-4-ylpiperidine-4-carboxamide;2,2,2-trifluoroacetic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20BrF4N3O5
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