You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6-(2,5-dimethoxyphenyl)-4,7,8-trimethyl-2-(3-oxobutan-2-yl)-9aH-purino[7,8-a]imidazol-9-ium-1,3-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C22H26N5O5+
assistant