56278...61039 (3522-digits)

This number is a prime.

In binary notation, the proven prime 2^0 + 2^1 + 2^2 + 2^3 + 2^5 + 2^7 + 2^11 + ... + 2^11699 economically encodes, as zeros, all the composite natural numbers less than 11699. In decimal notation, it has 3522 digits. [Broadhurst]