The calculated distance (air line) between Katlenburg-Lindau and Düsseldorf is approximately 147 miles respectively 236 kilometers.
By car or train, the actual journey to Düsseldorf is certainly longer, as only the direct route (as the crow flies) between Katlenburg-Lindau and Düsseldorf has been calculated here.
Air line (approximately)
236 kilometers
127 nautical miles