Hex #557879 or rgb(85,120,121) in RGB space is the tint of cyan. It has hue angle of 181.67 degrees, value = 47 and saturation = 30. #557879 can be obtained by mixing 4 colors: 4 drops of magenta, 3 drops of cyan, 4 drops of green, 1 drop of black.
Nearest safe hex - #666666. Below you can see the block with #557879 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #557879 to the mixer and play with it.