Hex #668d91 or rgb(102,141,145) in RGB space is the tint of cyan. It has hue angle of 185.58 degrees, value = 57 and saturation = 30. #668d91 can be obtained by mixing 4 colors: 1 drop of red, 4 drops of blue, 2 drops of green, 3 drops of white.
Nearest safe hex - #669999. Below you can see the block with #668d91 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #668d91 to the mixer and play with it.