Hex #00645c or rgb(0,100,92) in RGB space is the tint of cyan. It has hue angle of 175.20 degrees, value = 39 and saturation = 100. #00645c can be obtained by mixing 4 colors: 4 drops of blue, 2 drops of cyan, 3 drops of green, 4 drops of black.
Nearest safe hex - #006666. Below you can see the block with #00645c color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #00645c to the mixer and play with it.