Hex #556739 or rgb(85,103,57) in RGB space is the tint of olive. It has hue angle of 83.48 degrees, value = 40 and saturation = 45. #556739 can be obtained by mixing 3 colors: 1 drop of yellow, 1 drop of blue, 1 drop of black.
Nearest safe hex - #666633. Below you can see the block with #556739 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556739 to the mixer and play with it.