Hex #555b5b or rgb(85,91,91) in RGB space is the tint of cyan. It has hue angle of 180.00 degrees, value = 36 and saturation = 7. #555b5b can be obtained by mixing 4 colors: 5 drops of red, 5 drops of blue, 2 drops of cyan, 3 drops of green.
Nearest safe hex - #666666. Below you can see the block with #555b5b color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #555b5b to the mixer and play with it.