Hex #669f44 or rgb(102,159,68) in RGB space is the tint of grass green. It has hue angle of 97.58 degrees, value = 62 and saturation = 57. #669f44 can be obtained by mixing 3 colors: 2 drops of yellow, 2 drops of blue, 1 drop of green.
Nearest safe hex - #669933. Below you can see the block with #669f44 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #669f44 to the mixer and play with it.