You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[2-(3,5-dimethylphenyl)ethyl]-3-ethyl-2-[2-(4-methylpiperazin-1-yl)propyl]guanidine;hydroiodide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H38IN5
assistant