You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-methyl-1-(7-methyl-5,11,14,15-tetrazapentacyclo[10.8.0.02,10.04,8.013,17]icosa-1(12),2,4(8),9,13(17),15-hexaen-5-yl)propan-1-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H24N4O
assistant