You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named ethyl 4-[4-(3-cyanopyridin-2-yl)-1,4-diazepan-1-yl]-5-methylthieno[2,3-d]pyrimidine-6-carboxylate is given. What is its corresponding molecular formula?
user
C21H22N6O2S
assistant