You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-methyl-1-[2-(2-methyl-1,3-thiazol-4-yl)ethyl]-3-[(2-phenylmethoxypyridin-4-yl)methyl]guanidine;hydroiodide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H26IN5OS
assistant