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 6-(2-ethoxyphenyl)-4,7-dimethyl-2-(2-methylprop-2-enyl)purino[7,8-a]imidazole-1,3-dione .
user
C21H23N5O3
assistant