You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S)-N-(2-chloro-5-nitrophenyl)-2-[methyl-[(2-piperidin-1-ylphenyl)methyl]amino]propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C22H27ClN4O3
assistant