You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-(4-chlorophenyl)-2-(2,4-dichlorophenyl)-6-(4-propanoylpiperazin-1-yl)pyrimidin-4-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H21Cl3N4O2
assistant