The firmware version is V18.104.22.168.NAMMIEI and it brings Android 7.1 Nougat, Xiaomi's Smart app launcher, image search, split screen multitasking and much more.
Great update (Android 7.1.2 and Miui 9.1.1). This phone right now works even better than before. Thanks Xiaomi.
xiaomi updated redmi 4 to android 7.1 with MIUI 8.5 only
Got that over a week ago in east europe. ( global, not beta )