9999999900000001

This number is a prime.

Just showing those entries submitted by 'Kuhn': (Click here to show all)

9999999900000001 = 10^8+99999999^2, 999999000001 = 10^6+999999^2, 99990001 = 10^4+9999^2, 9901 = 10^2+99^2 are the unique expressions (as sums of squares) of four primes. Very likely theses are the only primes of this form. [Kuhn]