Hex #556b71 or rgb(85,107,113) in RGB space is the tint of bluish cian. It has hue angle of 192.86 degrees, value = 44 and saturation = 25. #556b71 can be obtained by mixing 4 colors: 2 drops of red, 3 drops of cyan, 1 drop of white, 3 drops of black.
Nearest safe hex - #666666. Below you can see the block with #556b71 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556b71 to the mixer and play with it.