“HUMAN DNA has approximately 3 billion base pairs, according to the National Human Genome Research Institute. That means 4^3,000,000,000 possible base sequences. For simplicity, let’s say that each gene is either suppressed, or not, in the epigenome. That would be a binary choice for each gene. Most humans have between 20,000 and 25,000 genes. Let’s say the average is about 2^22,500 more choices.”
http://www.decodedscience.org/comparing-genetic-code-dna-binary-code/55476