You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named [3,3-dimethyl-4-(2-phenyltetrazole-5-carbonyl)piperazin-1-yl]-[6-(trifluoromethyl)pyridin-2-yl]methanone by IUPAC nomenclature, provide its molecular formula.
user
C21H20F3N7O2
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