Hendek is a municipality and district of Sakarya Province, Turkey. Its area is 646 km, and its population is 90,153. The municipality was founde…Hendek is a municipality and district of Sakarya Province, Turkey. Its area is 646 km, and its population is 90,153. The municipality was founded in 1907. The mayor of the city is Irfan Püsküllü.