You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance propan-2-yl 16-ethyl-4-methyl-3,6,11-triaza-14-azoniatetracyclo[8.7.0.02,7.012,17]heptadeca-1,4,6,8,10,12,14,16-octaene-15-carboxylate .
user
C20H21N4O2+
assistant