Hex #669c88 or rgb(102,156,136) in RGB space is the tint of greenish cian. It has hue angle of 157.78 degrees, value = 61 and saturation = 35. #669c88 can be obtained by mixing 4 colors: 1 drop of yellow, 1 drop of red, 1 drop of blue, 2 drops of cyan.
Nearest safe hex - #669999. Below you can see the block with #669c88 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #669c88 to the mixer and play with it.