Yemen (full name, Republic of Yemen) covers an area of approximately 537,000 sq km. Its terrain consists of a narrow coastal plain backed by flat-topped hills and rugged mountains; and a dissected upland desert plain rising to the desert interior. Yemen borders Oman and Saudi Arabia, and has 1,906 km of coastline. The country is divided into 19 governorates: Abyan, 'Adan, Ad Dali', Al Bayda', Al Hudaydah, Al Jawf, Al Mahrah, Al Mahwit, 'Amran, Dhamar, Hadramawt, Hajjah, Ibb, Lahij, Ma'rib, Sa'dah, San'a', Shabwah and Ta'izz. Sanaa is the capital, with a time difference of 3 hours ahead of GMT. The currency is the Yemeni riyal, and exports include crude oil, cotton, coffee and fish. The population of approximately 23,800,000 people comprises an ethnic makeup that is mostly Arab. The primary language is Arabic, and the predominant religion is Islam.