Simplify the following text for a Grade 4 native English-speaking person.
Original: The civil parish has an area of 21.51 k and in the 2001 census had a population of 15,659 in 6,941 households . For the purposes of local government , Dereham falls within , and is the center of administration for , the district of Breckland .
Simplified: In 2001 there were 15,659 people living in Dereham .