You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1,1,2,5,5,6,6-heptadeuterio-6-(3,4-dimethoxyphenyl)-1-(3-methylphenoxy)hexan-2-ol is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H28O4
assistant