Hex #558f98 or rgb(85,143,152) in RGB space is the tint of bluish cian. It has hue angle of 188.06 degrees, value = 60 and saturation = 44. #558f98 can be obtained by mixing 4 colors: 1 drop of yellow, 5 drops of blue, 1 drop of green, 2 drops of white.
Nearest safe hex - #669999. Below you can see the block with #558f98 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #558f98 to the mixer and play with it.