You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[4-(3-methyltriazolo[4,5-d]pyrimidin-7-yl)piperazin-1-yl]-(4-phenylphenyl)methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H21N7O
assistant