562949953421311

This number is a composite.

                                                            56294 9953421311

The largest known semiprime of the form 2^n^2-1. Since 2^n^2-1 will always divisible by 2^n-1, then it is clear that 2^n^2-1 could be a semiprime if and only if 2^n-1 is prime. Base on this fact, then, the next semiprime of the form 2^n^2-1 will have more than 5 million digits. [Tolgede]