Some amount of dichloromethane CH$$_2$$Cl$$_2$$ is added to 671.141 mL of chloroform CHCl$$_3$$ to prepare $$2.6 \times 10^{-3}$$ M solution of CH$$_2$$Cl$$_2$$ DCM. The concentration of DCM is ______ ppm (by mass).
Given: Atomic mass: C = 12; H: 1; Cl = 35.5 density of CHCl$$_3$$ = 1.49 g cm$$^{-3}$$