"The population of the city, as reported in the 1871 Census, was 367,552; in 1881, 405,848; in 1891, 452,518; in 1901, 509, 346; in 1911, 518,660; in 1921, 526,912; and in 1931, 647,230."
January 1, 1970
https://en.wikiquote.org/wiki/Chennai