You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-methoxy-4-(6-phenyl-6-pyridin-4-yl-1,7-dihydroindazol-3-yl)-1,2,5-thiadiazole The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H17N5OS
assistant