You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule N-[1,3-bis(2-fluorophenyl)propan-2-yl]-3-(difluoromethyl)-[1,2,4]triazolo[4,3-b]pyridazin-6-amine ?
user
C21H17F4N5
assistant