You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[2-ethoxy-3-[(3-methylimidazo[4,5-b]pyridine-7-carbonyl)amino]propyl]-3-methylimidazo[4,5-b]pyridine-7-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H24N8O3
assistant