You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 4-[6-(2-methyl-2,3-dihydroindole-1-carbonyl)pyrimidin-4-yl]piperazine-1-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H25N5O3
assistant