You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-chloro-2-[4-(4-pyrimidin-2-ylpiperazine-1-carbonyl)anilino]-5,7-dihydropyrimido[5,4-d][1]benzazepin-6-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C27H23ClN8O2
assistant