There are approximately ten times as many bacterial cells in the human microbiota as there are human cells in the body, with their largest number being in the gut flora, and a large number on the skin.
There are approximately 39 trillion bacterial cells in the human microbiota as personified by an "reference" 70kg male 170 cm tall, whereas there are 30 trillion human cells in the body. The largest number exist in the gut flora, and a large number on the skin.