Unable to answer "What’s the house number of this building?" for https://osm.org/way/684888882 via StreetComplete 45.1:

This is not a separate building. It's simply part of a larger building,and has been mapped separately just to better model the real world geometry. Also, it's abandoned/in ruins.

Furthermore, there's no house number. There's an inscription in the entrance (see attached photo) but I couldn't read it.

Attached photo(s):
https://westnordost.de/p/104695.jpg
https://westnordost.de/p/104696.jpg
https://westnordost.de/p/104697.jpg
https://westnordost.de/p/104698.jpg
https://westnordost.de/p/104699.jpg
https://westnordost.de/p/104700.jpg