Hex #667b5e or rgb(102,123,94) in RGB space is the tint of grass green. It has hue angle of 103.45 degrees, value = 48 and saturation = 24. #667b5e can be obtained by mixing 4 colors: 3 drops of magenta, 1 drop of blue, 5 drops of green, 1 drop of white.
Nearest safe hex - #666666. Below you can see the block with #667b5e color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #667b5e to the mixer and play with it.