The density of  inhabitents in  the urban region of Hanoi is 4,800/km 2  (12,000/sq mi) .  The city area code is +374 10 . 2,813/km 2  (7,290/sq mi) is the density of inhabitents in  the metro region of Hanoi . The city land area is 11,609.91 km 2  (4,482.61 sq mi) . The area of the city is 385.8 sq mi (999.3 sq km ) . The city Hanoi demonym is Barranquillero/a . The water area of the city is 4.46 sq km  (1.72 sq mi) . The area of the urban region is 14.0 sq mi (36 km 2 ) . On March 6, 1836 (city) the city was incorporated . Populations (2019): 3,731,447 is the population of the metro region of Hanoi . Hanoi is named for Confluence of Grand River and Gunnison River . Tang Liangzhi is the mayor of Hanoi . Hanoi is the government of National Park Service . The lowest elevation of Hanoi is 190 m  . The density of  inhabitents in Hanoi is 5,300/km 2  (14,000/sq mi) . Hanoi is at an elevation of 2250 m . The postal code of the city is 130000
There are more than 12470 residents per sq mi in the urban region of Hanoi