Hex #556b79 or rgb(85,107,121) in RGB space is the tint of blue. It has hue angle of 203.33 degrees, value = 47 and saturation = 30. #556b79 can be obtained by mixing 4 colors: 1 drop of yellow, 4 drops of blue, 3 drops of white, 4 drops of black.
Nearest safe hex - #666666. Below you can see the block with #556b79 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #556b79 to the mixer and play with it.