There is no simple formula for #697166, but we have one for color #707e6b, that is similar to #697166 by 97.4%.
Color #707e6b name: dark grayish grass green
Hex #707e6b or rgb(112,126,107) in RGB space is the tint of grass green. It has hue angle of 104.21 degrees, value = 49 and saturation = 15. #707e6b can be obtained by mixing 4 colors: 3 drops of yellow, 4 drops of blue, 4 drops of white, 5 drops of black.
Nearest safe hex - #666666. Below you can see the block with #707e6b color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #707e6b to the mixer and play with it.