You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[[2-(dimethylamino)pyridin-4-yl]methyl]-3-[3-(N-ethylanilino)propyl]-2-methylguanidine;hydroiodide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H33IN6
assistant