You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-ethyl-2-[(3-fluoro-4-methoxyphenyl)methyl]-3-(4-methyl-2-morpholin-4-ylpentyl)guanidine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H35FN4O2
assistant