Hex #66d580 or rgb(102,213,128) in RGB space is the tint of bluish green. It has hue angle of 134.05 degrees, value = 84 and saturation = 52. #66d580 can be obtained by mixing 3 colors: 4 drops of yellow, 5 drops of cyan, 1 drop of black.
Nearest safe hex - #66cc99. Below you can see the block with #66d580 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #66d580 to the mixer and play with it.