Complex sentence: The town of Kotlas serves as the administrative center of the district, although is not administratively a part of it and, together with one work settlement (Vychegodsky) and two rural localities, is incorporated separately as a town of oblast significance.
Split into simpler sentences: The town of Kotlas serves as the administrative center of the district, although is not administratively a part of it. Administratively, along with one work settlement (Vychegodsky) and two rural localities, it is incorporated separately as a town of oblast significance.