You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(4,4-dimethylcyclohexyl)-6-[(1S)-2-pyrimidin-2-ylcyclobutyl]-5H-pyrazolo[3,4-d]pyrimidin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H26N6O
assistant