'''Sudan''' ( or ; ), officially the '''Republic of the Sudan'''  (), is a country in Northeast Africa. It borders the countries of Central African Republic, Chad, Egypt, Eritrea, Ethiopia, Libya, South Sudan, and the Red Sea. It has a population of 44.91 million people as of 2021 and occupies 1,886,068 square kilometres (728,215 square miles), making it Africa's third-largest country by area, and the third-largest by area in the Arab League. It was the largest country by area in Africa and the Arab League until the secession of South Sudan in 2011, since which both titles have been held by Algeria. Its capital is Khartoum and its most populated city is Omdurman (part of metro Khartoum).