You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 6-(3,4-dimethylphenyl)-4,7,8-trimethyl-2-propyl-4a,9a-dihydropurino[7,8-a]imidazole-1,3-dione .
user
C21H27N5O2
assistant