Hex #666580 or rgb(102,101,128) in RGB space is the tint of violet. It has hue angle of 242.22 degrees, value = 50 and saturation = 21. #666580 can be obtained by mixing 4 colors: 3 drops of magenta, 3 drops of blue, 3 drops of green, 1 drop of white.
Nearest safe hex - #666699. Below you can see the block with #666580 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #666580 to the mixer and play with it.