Hex #668f55 or rgb(102,143,85) in RGB space is the tint of grass green. It has hue angle of 102.41 degrees, value = 56 and saturation = 41. #668f55 can be obtained by mixing 4 colors: 1 drop of yellow, 5 drops of red, 5 drops of cyan, 4 drops of green.
Nearest safe hex - #669966. Below you can see the block with #668f55 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #668f55 to the mixer and play with it.