Hex #66dc4d or rgb(102,220,77) in RGB space is the tint of grass green. It has hue angle of 109.51 degrees, value = 86 and saturation = 65. #66dc4d can be obtained by mixing 3 colors: 4 drops of yellow, 3 drops of cyan, 3 drops of green.
Nearest safe hex - #66cc66. Below you can see the block with #66dc4d color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66dc4d to the mixer and play with it.