You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-chloro-7-[(3-chloro-1-propan-2-ylindazol-5-yl)methoxy]-2H-chromene-3-carbaldehyde The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H18Cl2N2O3
assistant