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-[2-(2,5-dichlorophenoxy)-6-(1,5-dimethyl-6-oxopyridin-3-yl)pyrimidin-4-yl]butane-1-sulfonamide ?
user
C21H22Cl2N4O4S
assistant