The calculated distance (air line) between Otopeni and Piatra Neamţ is approximately 164 miles respectively 264 kilometers.
By car or train, the actual journey to Piatra Neamţ is certainly longer, as only the direct route (as the crow flies) between Otopeni and Piatra Neamţ has been calculated here.
Air line (approximately)
264 kilometers
142 nautical miles