Hex #556a72 or rgb(85,106,114) in RGB space is the tint of bluish cian. It has hue angle of 196.55 degrees, value = 45 and saturation = 25. #556a72 can be obtained by mixing 4 colors: 5 drops of red, 4 drops of blue, 4 drops of cyan, 2 drops of green.
Nearest safe hex - #666666. Below you can see the block with #556a72 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556a72 to the mixer and play with it.