Hex #559d8e or rgb(85,157,142) in RGB space is the tint of greenish cian. It has hue angle of 167.50 degrees, value = 62 and saturation = 46. #559d8e can be obtained by mixing 4 colors: 5 drops of blue, 4 drops of green, 5 drops of white, 1 drop of black.
Nearest safe hex - #669999. Below you can see the block with #559d8e color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #559d8e to the mixer and play with it.