Hex #666556 or rgb(102,101,86) in RGB space is the tint of yellow. It has hue angle of 56.25 degrees, value = 40 and saturation = 16. #666556 can be obtained by mixing 4 colors: 2 drops of yellow, 2 drops of red, 5 drops of blue, 1 drop of green.
Nearest safe hex - #666666. Below you can see the block with #666556 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #666556 to the mixer and play with it.