Hex #555739 or rgb(85,87,57) in RGB space is the tint of yellow. It has hue angle of 64.00 degrees, value = 34 and saturation = 34. #555739 can be obtained by mixing 4 colors: 4 drops of yellow, 1 drop of red, 5 drops of blue, 5 drops of black.
Nearest safe hex - #666633. Below you can see the block with #555739 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #555739 to the mixer and play with it.