You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(2-bromo-4-methylphenyl)-2-[4-(5-methylpyridin-2-yl)oxypiperidin-1-yl]propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H26BrN3O2
assistant