You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-benzyl-2-[[5-(4-bromophenyl)-4-imino-3-methyl-2H-pyrazolo[3,4-d]pyrimidin-6-yl]sulfanyl]acetamide by IUPAC nomenclature, provide its molecular formula.
user
C21H19BrN6OS
assistant