Hex #551b1d or rgb(85,27,29) in RGB space is the tint of red. It has hue angle of 357.93 degrees, value = 33 and saturation = 68. #551b1d can be obtained by mixing 4 colors: 4 drops of red, 2 drops of blue, 1 drop of green, 5 drops of black.
Nearest safe hex - #663333. Below you can see the block with #551b1d color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #551b1d to the mixer and play with it.