You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R,3S)-2-(carbamoylamino)-N-[4-[1-(difluoromethyl)benzimidazol-2-yl]phenyl]-3-methylpentanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H23F2N5O2
assistant