It is a weak prime.
It is a cyclic number.
It is a congruent number.
Almost surely, 2121220111155471 is an apocalyptic number.
121220111155471 is an equidigital number, since it uses as much as digits as its factorization.
121220111155471 is an evil number, because the sum of its binary digits is even.
Adding to 121220111155471 its reverse (174551111022121), we get a palindrome (295771222177592).
The spelling of 121220111155471 in words is "one hundred twenty-one trillion, two hundred twenty billion, one hundred eleven million, one hundred fifty-five thousand, four hundred seventy-one".