You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 1-ethyl-2-[[1-(2-methoxyethyl)cyclobutyl]methyl]-3-[3-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-yl)propyl]guanidine .
user
C21H38N6O
assistant