You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[2-(4-bromo-2-methylanilino)-2-oxoethyl] (3R)-1-(3-methylphenyl)-5-oxopyrrolidine-3-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H21BrN2O4
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