You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-methyl-1-[[1-(2-methylpropyl)imidazol-2-yl]methyl]-3-[1-(5-methylpyridin-2-yl)piperidin-4-yl]guanidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H33N7
assistant