Hex #669c89 or rgb(102,156,137) in RGB space is the tint of greenish cian. It has hue angle of 158.89 degrees, value = 61 and saturation = 35. #669c89 can be obtained by mixing 4 colors: 3 drops of yellow, 5 drops of blue, 1 drop of cyan, 1 drop of white.
Nearest safe hex - #669999. Below you can see the block with #669c89 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #669c89 to the mixer and play with it.