You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[5-[[2-amino-2-(4-methylphenyl)acetyl]amino]-2-methylphenyl]-2,2-dimethylpropanamide;hydrochloride is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H28ClN3O2
assistant