Hex #663691 or rgb(102,54,145) in RGB space is the tint of purple. It has hue angle of 271.65 degrees, value = 57 and saturation = 63. #663691 can be obtained by mixing 4 colors: 3 drops of magenta, 4 drops of blue, 1 drop of white, 2 drops of black.
Nearest safe hex - #663399. Below you can see the block with #663691 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #663691 to the mixer and play with it.