Iran, also called Persia, and officially the Islamic Republic of Iran, is a country in Western Asia. It is bordered to the northwest by Armenia and Azerbaijan, to the north by the Caspian Sea, to the northeast by Turkmenistan, to the east by Afghanistan and Pakistan, to the south by the Persian Gulf and the Gulf of Oman, and to the west by Turkey and Iraq. Its central location in Eurasia and proximity to the Strait of Hormuz give it significant geostrategic importance. Tehran is the capital and largest city, as well as the leading economic and cultural hub; it is also the most populous city in Western Asia, with more than 8.8 million residents, and up to 15 million including the metropolitan area. With 83 million inhabitants, Iran is the world's 17th most populous country. Spanning 1,648,195 km2 (636,372 sq mi), it is the second largest country in the Middle East and the 17th largest in the world.