The
六 in
六安 is pronounced lù, NOT liù. This preserves an archaic reading from the Han dynasty
六安国. In 2016 CCTV news anchors briefly switched to 'liù'an' per dictionary reform, causing public backlash; officials restored lù as the accepted local pronunciation. Treat this as a named-exception just like
铅山 (Yánshān, not qiān).