Virtually all scanners are 36 bits now, and some are 42 bits. More bits support more dynamic range, but does not ensure it exists. More bits are required to hold numeric values containing better dynamic range, but this one detail does not ensure it. While the two factors are often associated, there is also a second requirement. Image density is measured from image brightness with optical densiometers, and ranges from 0 to 4, where 0 is pure white and 4 is very black.
More density is less brightness.
Density of 3.0 is 10 times greater intensity than a density of 2.0. Density 4.0 is not a theoretical maximum, the math is not limited, but it is a practical maximum of density, because nothing you can scan will reach 4.0. The minimum and maximum values of density capable of being captured by a specific scanner are called DMin and DMax. If the scanner's DMin were 0.2 and DMax were 3.1, its Dynamic Range would be 2.9. DMax implies unique image tone values are distinguishable, and not hidden by electronic noise.