Query: What's the estimated population of Southampton?
Context: It lies at the northernmost point of Southampton Water at the confluence of the River Test and River Itchen, with the River Hamble joining to the south of the urban area. The city, which is a unitary authority, has an estimated population of 253,651. The city's name is sometimes abbreviated in writing to "So'ton" or "Soton", and a resident of Southampton is called a Sotonian.