Apparently the Antonov An-2 [1] can also fly backwards. There is no published stall speed in the flight manual and realistically it's around 25 kt (50 km/h).

[1] https://en.wikipedia.org/wiki/Antonov_An-2

AN-2 doesn't stall (with power on)... it just mushes and descendeds at a few hundred feet per minute. Emergency procedure is to just hold the stick aft and give it power. Almost like descending under a parachute.

Fun fact, Antonov was responsible for the Soviet effort to copy the Storch, years before designing the An-2.