From the Wikipedia page [1]
Niamey Capital District is the capital district of Niger. It has an area of 670 km2 and a 2012 census count final adjustment of 1,026,848 people. The same population figures indicate that Niamey, the eponymous city or settlement itself, is smaller than the capital district in total area and that there are other settlements within. The capital district is projected by the Institut National de la Statistique du Niger (website) to have 1,203,800 residents as of 2017.The capital district population growth rate is lower than the torrid national rate, suggesting large rural migration (urbanization) is negligible in Niger, there is an undercount, and/or the government's forced urban to rural deportations are effective.