As for how I found out ahead of time: someone jumped the gun and added it prematurely to Wikipedia. The edit was quickly reverted, but it remained in the history.
I'm amused to see that @standupmaths's video on this newly-discovered prime actually makes use of the property I mentioned in my first post: that it fits neatly into an 80-column terminal window.
I found out the exponent of the new Mersenne prime before it’s been officially announced, and I feel as though I’m in possession of a deep, dark secret.
I hope I’m not giving too much away if I remark that in base 10 it has a number of digits that is a multiple of 80, which means it scrolls very neatly down a standard-width terminal.