According to published reports in the Korean media, Samsung shipped 20 Million Galaxy S4 smartphones in the first two months. Despite total sales estimates being down to 6.5 Million in July, the phone has sold phenomenally well overall. Samsung originally envisioned selling 50 Million units of the SGS4, and that is still possible considering they are already almost halfway there. To put it in perspective, the SGS3 took over 100 days to hit that same 20 Million milestone. Incidentally, the SGS3 is still selling well too, which perhaps bodes well for total sales of the SGS4 in the future.
Source: UnWiredView