Hex #556839 or rgb(85,104,57) in RGB space is the tint of olive. It has hue angle of 84.26 degrees, value = 41 and saturation = 45. #556839 can be obtained by mixing 4 colors: 1 drop of yellow, 3 drops of red, 4 drops of blue, 4 drops of green.
Nearest safe hex - #666633. Below you can see the block with #556839 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556839 to the mixer and play with it.