Hex #666444 or rgb(102,100,68) in RGB space is the tint of yellow. It has hue angle of 56.47 degrees, value = 40 and saturation = 33. #666444 can be obtained by mixing 4 colors: 3 drops of yellow, 1 drop of red, 4 drops of blue, 2 drops of black.
Nearest safe hex - #666633. Below you can see the block with #666444 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #666444 to the mixer and play with it.