Saudi Arabia, officially the Kingdom of Saudi Arabia, is a country in Western Asia constituting the vast majority of the Arabian Peninsula. With a land area of approximately 2,150,000 km2 (830,000 sq mi), Saudi Arabia is geographically the largest sovereign state in Western Asia, the second-largest in the Arab world (after Algeria), the fifth-largest in Asia, and the 12th-largest in the world. Saudi Arabia is bordered by Jordan and Iraq to the north, Kuwait to the northeast, Qatar, Bahrain, and the United Arab Emirates to the east, Oman to the southeast and Yemen to the south; it is separated from the Sinai (Egypt) in the north-west by the Gulf of Aqaba. Saudi Arabia is the only country with both a Red Sea coast and a Persian Gulf coast, and most of its terrain consists of arid desert, lowland and mountains. As of October 2018, the Saudi economy was the largest in the Middle East and the 18th largest in the world. Saudi Arabia also has one of the world's youngest populations, with approximately 50 percent of its population of 34.2 million being under 25 years old.