Republic of Iran, is a country in Western Asia.[13][14][15] It is bordered to the northwest by Armenia and Azerbaijan, with Kazakhstan and Russia across 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. Comprising a land area of 1,648,195 km2 (636,372 sq mi), it is the second-largest nation in the Middle East and the 18th-largest in the world; with 78.4 million inhabitants, Iran is the world's 17th most populous nation.[13][16] It is the only country that has both a Caspian Sea and Indian Ocean coastline. Iran has been of geostrategic importance because of its central location in Eurasia and Western Asia and the Strait of Hormuz.