Hex #509c40 or rgb(80,156,64) in RGB space is the tint of grass green. It has hue angle of 109.57 degrees, value = 61 and saturation = 59. #509c40 can be obtained by mixing 4 colors: 5 drops of yellow, 4 drops of cyan, 2 drops of green, 5 drops of black.
Nearest safe hex - #669933. Below you can see the block with #509c40 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #509c40 to the mixer and play with it.