Hex #555768 or rgb(85,87,104) in RGB space is the tint of violet. It has hue angle of 233.68 degrees, value = 41 and saturation = 18. #555768 can be obtained by mixing 4 colors: 3 drops of red, 1 drop of blue, 3 drops of cyan, 2 drops of black.
Nearest safe hex - #666666. Below you can see the block with #555768 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #555768 to the mixer and play with it.