Teaser 2862: Algebria’s standard

From The Sunday Times, 30th July 2017 [link]

The Algebrian rectangular flag is highly symbolic. Each of its sides is an even number of inches long and a diagonal divides it into two triangles, one blue and one green, representing its two founding tribes. The length of the diagonal (in inches) is the number of states in Algebria, and the area of the flag (in square inches) is the twentieth century year in which the country obtained independence.

How many states are there in Algebria, and in which year did the country obtain independence?

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