The typical smartphone carries some 25,000 microorganisms, a mix of bacteria and fungi. This is a relatively high number compared with other objects, although whether these microbes are pathogenic depends upon what the user has been up to. The greatest chance of there being pathogens on an object invariably comes down to whether or not someone has washed their hands after visiting the toilet.
So what is cleaner than the smartphone? Surprisingly, one of the five is the toilet. This is because lavatories are normally sanitized fairly often (at least the ones in public buildings, what people do in their own homes is another matter.)
Smartphone screens treated with Kastus Log4+ will clean themselves by killing 99.99% of bacteria and fungi.