Hex #555000 or rgb(85,80,0) in RGB space is the tint of yellow. It has hue angle of 56.47 degrees, value = 33 and saturation = 100. #555000 can be obtained by mixing 3 colors: 3 drops of red, 4 drops of green, 2 drops of black.
Nearest safe hex - #666600. Below you can see the block with #555000 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #555000 to the mixer and play with it.