Mortsel is a city and municipality close to the city of Antwerp located in the Belgian province of Antwerp. The municipality only comprises the city of Mortsel proper. On January 1, 2006 Mortsel had a total population of 24,427 people. The total area is 7.78 km² which gives a population density of 3,138 inhabitants per km². This is the highest population density of any municipality in the Flemish Region (Flanders), and second-highest (to Saint-Nicolas) outside the Brussels-Capital Region.