As of 2015 , it had a registered population of 644,300 and a resident population of 589,400 .
Yizhang County covers 2,142.7 km ( 827.3 sq mi ) .
As of 2015 , Yizhang County had a registered population of 644,300 and a resident population of 589,400 .
Yizhang County covers 2,142.7 km ( 827.3 sq mi ) .