Hex #15a379 or rgb(21,163,121) in RGB space is the tint of greenish cian. It has hue angle of 162.25 degrees, value = 64 and saturation = 87. #15a379 can be obtained by mixing 4 colors: 1 drop of yellow, 4 drops of blue, 3 drops of cyan, 4 drops of green.
Nearest safe hex - #009966. Below you can see the block with #15a379 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #15a379 to the mixer and play with it.