Hex #664b8e or rgb(102,75,142) in RGB space is the tint of purple. It has hue angle of 264.18 degrees, value = 56 and saturation = 47. #664b8e can be obtained by mixing 4 colors: 3 drops of magenta, 5 drops of blue, 3 drops of white, 4 drops of black.
Nearest safe hex - #663399. Below you can see the block with #664b8e color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #664b8e to the mixer and play with it.