You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5E)-5-[[5-(2-chlorophenyl)furan-2-yl]methylidene]-4-methyl-2,6-dioxo-1-propylpyridine-3-carbonitrile The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H17ClN2O3
assistant