You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-[5-chloro-2-methoxy-6-(triazol-2-yl)pyridin-3-yl]-3-[7-(2-ethoxyethyl)-2-methyl-[1,3]thiazolo[5,4-b]pyridin-6-yl]urea by IUPAC nomenclature, provide its molecular formula.
user
C20H21ClN8O3S
assistant