You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(2-chlorophenyl)-4-[3-[methyl-(1-methylpyrrolidin-3-yl)amino]propanoyl]piperazin-2-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H27ClN4O2
assistant