1, 2009) [1]  - Total 7,162,864 ( 1st in Vietnam )   - Density 8,851/sq mi (3,419/km 2 ) Area code(s) +84 (8) Saigon  ( Vietnamese :  Sài Gòn ) is the  largest city  in  Vietnam . It was once known as  Prey Nokor , an important  Khmer  sea port prior