17069...58001 (47-digits)

This number is a prime.

                         1706917 4130723235 9586106430 2905931475 6045558001

The smallest prime of the form a^a+b^b+c^c ... = 3^3+7^7+31^31, where a,b,c are Mersenne primes. Note that these are consecutive Mersenne primes. [Sariyar]