20479

This number is a prime.

The largest prime less than a googol of form (x-1)*2^x-1, where x is a prime, case x=11), i.e., 10*2^11-1=20479. [Loungrides]

The only prime number p for which the floor functions of p times the square root of two (28961) and p times the square root of three (35470) together contain the ten digits once each. [Gaydos]