You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[3-[[ethylamino-[4-[2-(methylamino)-2-oxoethyl]piperidin-1-yl]methylidene]amino]propyl]benzamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H33N5O2
assistant