You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-N-[2-(4-chlorophenyl)propan-2-ylcarbamoyl]-N-[(2R)-2-hydroxybutyl]-2-(3-methyl-1,2-oxazol-5-yl)propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H28ClN3O4
assistant