Iran (/aɪˈræn/ or Listeni/ɪˈrɑːn/;[11] Persian: ایران‎‎ – Irān [ʔiːˈɾɒːn] ( listen)), also known as Persia (/ˈpɜːrʒə/ or /ˈpɜːrʃə/),[12] officially the Islamic Republic of Iran (جمهوری اسلامی ایران – Jomhuri ye Eslāmi ye Irān [d͡ʒomhuːˌɾiːje eslɒːˌmiːje ʔiːˈɾɒːn]), is a sovereign state in Western Asia.[13][14] It is bordered to the northwest by Armenia, the de facto Nagorno-Karabakh Republic, and Azerbaijan; to the northeast by Turkmenistan; to the east by Afghanistan and Pakistan; to the south by the Persian Gulf and the Gulf of Oman; to the north by the Caspian Sea; 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 country in the Middle East and the 18th-largest in the world. With 78.4 million inhabitants, Iran is the world's 17th-most-populous country.[15][16] It is the only country with both a Caspian Sea and an Indian Ocean coastline. The country's central location in Eurasia and Western Asia, and its proximity to the Strait of Hormuz, make it of great geostrategic importance.[17] Tehran is the country's capital and largest city as well as its leading economic center.