Hex #666b6f or rgb(102,107,111) in RGB space is the tint of blue. It has hue angle of 206.67 degrees, value = 44 and saturation = 8. #666b6f can be obtained by mixing 4 colors: 2 drops of yellow, 2 drops of red, 5 drops of blue, 1 drop of cyan.
Nearest safe hex - #666666. Below you can see the block with #666b6f color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #666b6f to the mixer and play with it.