You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[2-[4-(cyclopentanecarbonyl)piperazin-1-yl]ethyl]-3-ethyl-2-(4-methylpentyl)guanidine;hydroiodide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H42IN5O
assistant