11111...11111 (271-digits)

This number is a probable-prime (likely to be a prime but we have not (re-)proven it on this site).

         1 1111111111 0001110001 1111111111 0001110001 1111111111 0001110001
1111111111 0001110001 1111111111 0001110001 1111111111 0001110001 1111111111
0001110001 1111111111 0001110001 1111111111 0001110001 1111111111 0001110001
1111111111 0001110001 1111111111 0001110001 1111111111 0001110001 1111111111

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

(((10^11-1)/9)*10^20+111*10^14)*(10^(13*20)-1)/((10^20-1)/1)+((10^11-1)/9) is a "tetradic super-palindromic prime" with many lines of symmetry. [Stath]