Hex #556b6b or rgb(85,107,107) in RGB space is the tint of cyan. It has hue angle of 180.00 degrees, value = 42 and saturation = 21. #556b6b can be obtained by mixing 4 colors: 4 drops of magenta, 2 drops of blue, 1 drop of cyan, 5 drops of green.
Nearest safe hex - #666666. Below you can see the block with #556b6b color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556b6b to the mixer and play with it.