Hex #5b6d68 or rgb(91,109,104) in RGB space is the tint of greenish cian. It has hue angle of 163.33 degrees, value = 43 and saturation = 17. #5b6d68 can be obtained by mixing 4 colors: 2 drops of yellow, 4 drops of blue, 3 drops of white, 5 drops of black.
Nearest safe hex - #666666. Below you can see the block with #5b6d68 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #5b6d68 to the mixer and play with it.