You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
9-[1-(dimethylamino)-3-methylbutan-2-yl]-N-propyl-9-azabicyclo[3.3.1]nonan-3-amine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H37N3
assistant