You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
19-bromo-13-methyl-3,13,23-triazahexacyclo[14.7.0.02,10.04,9.011,15.017,22]tricosa-1(16),4,6,8,17(22),18,20-heptaene-12,14-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H16BrN3O2
assistant