5,300/km 2  (14,000/sq mi) is the density of people in Hanoi . The city has the postal code 130000 . The demonym of the city Hanoi is Barranquillero/a . Hanoi is the government of National Park Service . This city is named after Confluence of Grand River and Gunnison River . +374 10 is the area code of Hanoi . The Hanoi citys' lowest elevation is 620 ft . The land area of the city is 11,609.91 km 2  (4,482.61 sq mi) . Tang Liangzhi is the mayor of Hanoi . 4,800/km 2  (12,000/sq mi) is the density of people in  the urban region of Hanoi . Populations (2019): 3,731,447 is the population of the metro region of Hanoi . The city was incorporated in March 6, 1836 (city) . The density of  people in  the metro region of Hanoi is 2,813/km 2  (7,290/sq mi) . The city is 385.8 sq mi (999.3 sq km ) in area . The urban region is 14.0 sq mi (36 km 2 ) in area . Hanoi is at an elevation of 2250 m . The city water area is 4.46 sq km  (1.72 sq mi)
Hanoi is governed by U.S. National Park Service