Hex #557d55 or rgb(85,125,85) in RGB space is the tint of green. It has hue angle of 120.00 degrees, value = 49 and saturation = 32. #557d55 can be obtained by mixing 3 colors: 2 drops of green, 3 drops of white, 4 drops of black.
Nearest safe hex - #666666. Below you can see the block with #557d55 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #557d55 to the mixer and play with it.