Hex #556d4e or rgb(85,109,78) in RGB space is the tint of grass green. It has hue angle of 106.45 degrees, value = 43 and saturation = 28. #556d4e can be obtained by mixing 4 colors: 1 drop of magenta, 3 drops of green, 3 drops of white, 5 drops of black.
Nearest safe hex - #666666. Below you can see the block with #556d4e color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556d4e to the mixer and play with it.