You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-N,1-N-dimethyl-3-[3-(5-methyl-4-phenylimidazol-1-yl)propylsulfanyl]benzene-1,2-diamine by IUPAC nomenclature, provide its molecular formula.
user
C21H26N4S
assistant