Hex #664739 or rgb(102,71,57) in RGB space is the tint of orange red. It has hue angle of 18.67 degrees, value = 40 and saturation = 44. #664739 can be obtained by mixing 4 colors: 3 drops of yellow, 3 drops of red, 5 drops of blue, 4 drops of black.
Nearest safe hex - #663333. Below you can see the block with #664739 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #664739 to the mixer and play with it.