Hex #668991 or rgb(102,137,145) in RGB space is the tint of bluish cian. It has hue angle of 191.16 degrees, value = 57 and saturation = 30. #668991 can be obtained by mixing 4 colors: 3 drops of red, 1 drop of magenta, 5 drops of cyan, 1 drop of green.
Nearest safe hex - #669999. Below you can see the block with #668991 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #668991 to the mixer and play with it.