Hex #5599a4 or rgb(85,153,164) in RGB space is the tint of bluish cian. It has hue angle of 188.35 degrees, value = 64 and saturation = 48. #5599a4 can be obtained by mixing 4 colors: 1 drop of blue, 4 drops of cyan, 5 drops of white, 5 drops of black.
Nearest safe hex - #669999. Below you can see the block with #5599a4 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #5599a4 to the mixer and play with it.