Hex #668688 or rgb(102,134,136) in RGB space is the tint of cyan. It has hue angle of 183.53 degrees, value = 53 and saturation = 25. #668688 can be obtained by mixing 4 colors: 2 drops of blue, 1 drop of green, 4 drops of white, 3 drops of black.
Nearest safe hex - #669999. Below you can see the block with #668688 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #668688 to the mixer and play with it.