You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(2R)-1-ethylpyrrolidin-2-yl]-N-[[2-[(2-fluorophenyl)methoxy]phenyl]methyl]methanamine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H27FN2O
assistant