You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-(difluoromethylsulfonyl)-N-[4-(6-imidazol-1-ylpyridazin-3-yl)oxyphenyl]benzamide by IUPAC nomenclature, provide its molecular formula.
user
C21H15F2N5O4S
assistant