The Democratic Republic of the Congo is often referred to as Congo-Kinshasa to distinguish it from the neighbouring Republic of the Congo, or Congo-Brazzaville, (Kinshasa and Brazzaville being the respective capitals). Congo-Kinshasa covers an area of approximately 2.34 million sq km and borders Angola, Burundi, Central African Republic, Republic of the Congo, Rwanda, Sudan, Tanzania, Uganda and Zambia, and has 37 km of coastline. The capital, Kinshasam, has a time zone 1 hour ahead of GMT. The currency is the Congolese franc, and exports include diamonds, copper, coffee, cobalt and crude oil. The population of approximately 69,000,000 people comprises over 200 African ethnic groups (mainly Bantu). The primary languages are French, Lingala, Kiswahili, Kikongo and Tshiluba, and the predominant religions are Christianity and Islam.