Hex #556a64 or rgb(85,106,100) in RGB space is the tint of greenish cian. It has hue angle of 162.86 degrees, value = 42 and saturation = 20. #556a64 can be obtained by mixing 4 colors: 1 drop of yellow, 2 drops of blue, 1 drop of white, 2 drops of black.
Nearest safe hex - #666666. Below you can see the block with #556a64 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556a64 to the mixer and play with it.