You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[4-[3-(4-fluorophenoxy)propyl]piperazin-1-yl]-[(3R)-1-propan-2-ylpyrrolidin-3-yl]methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H32FN3O2
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