The calculated distance (air line) between Al Qāhirah al Jadīdah and Diyarb Najm is approximately 49 miles respectively 79 kilometers.
By car or train, the actual journey to Diyarb Najm is certainly longer, as only the direct route (as the crow flies) between Al Qāhirah al Jadīdah and Diyarb Najm has been calculated here.
Air line (approximately)
79 kilometers
43 nautical miles