Hex #663633 or rgb(102,54,51) in RGB space is the tint of red. It has hue angle of 3.53 degrees, value = 40 and saturation = 50. #663633 can be obtained by mixing 4 colors: 1 drop of red, 3 drops of magenta, 3 drops of green, 3 drops of black.
Nearest safe hex - #663333. Below you can see the block with #663633 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #663633 to the mixer and play with it.