My pet theory is that the line on the right hand side of Wow.jpeg is somehow the answer, and the 51 character is just a red herring somehow. If it was just a transformation on the "private key" what was the point of the hidden swirls and lines on the image?
I've been saying this since yesterday. Vertical number sequence is:
27913579135791357913579135791357913579024
Notice that we have 'WRITTEN VERTICALLY' added to the image, although it is for 'TWO DIGITS'.
In the number sequence above series '13579' is repeated 7x, with '279' before and '024' after. I could not make anything out of it, but it's clearly underlined with blue stroke from image metadata.