You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-[4-(2-fluoro-4-methylphenyl)-1,4-diazepan-1-yl]-2-(4-methylcyclohexyl)oxyethanone by IUPAC nomenclature, provide its molecular formula.
user
C21H31FN2O2
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