You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[2-(2,3-dihydro-1,4-benzodioxin-6-yl)-2-oxoethyl]-6-(4-fluoro-2-methoxyphenyl)pyridazin-3-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H17FN2O5
assistant