You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 3-[6-(1,4-dioxa-8-azaspiro[4.5]decan-8-yl)-[1,2,4]triazolo[4,3-b]pyridazin-3-yl]-N-(2-fluorophenyl)propanamide .
user
C21H23FN6O3
assistant