Unable to answer "What’s the house number of this building?" – House – https://osm.org/way/867523108 via StreetComplete 59.2:

Has two signs one that says "seaway" on the driveway and one that says "seaways" on the house

Attached photo(s):
https://westnordost.de/p/245442.jpg
https://westnordost.de/p/245443.jpg