You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (2S)-2-[(4-chlorophenyl)methyl-[2-(2-fluorophenoxy)acetyl]amino]-N-propan-2-ylpropanamide by IUPAC nomenclature, provide its molecular formula.
user
C21H24ClFN2O3
assistant