Hex #559a8e or rgb(85,154,142) in RGB space is the tint of greenish cian. It has hue angle of 169.57 degrees, value = 60 and saturation = 45. #559a8e can be obtained by mixing 4 colors: 4 drops of blue, 3 drops of green, 4 drops of white, 1 drop of black.
Nearest safe hex - #669999. Below you can see the block with #559a8e color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #559a8e to the mixer and play with it.