211111110021961 has 2 divisors, whose sum is σ = 211111110021962. Its totient is φ = 211111110021960.

The previous prime is 211111110021943. The next prime is 211111110022049. The reversal of 211111110021961 is 169120011111112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 142591206616336 + 68519903405625 = 11941156^2 + 8277675^2 .

It is a cyclic number.

It is not a de Polignac number, because 211111110021961 - 2¹¹ = 211111110019913 is a prime.

It is not a weakly prime, because it can be changed into another prime (211111110091961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105555555010980 + 105555555010981.

It is an arithmetic number, because the mean of its divisors is an integer number (105555555010981).

Almost surely, 2^{211111110021961} is an apocalyptic number.

It is an amenable number.

211111110021961 is a deficient number, since it is larger than the sum of its proper divisors (1).

211111110021961 is an equidigital number, since it uses as much as digits as its factorization.

211111110021961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 28.

The spelling of 211111110021961 in words is "two hundred eleven trillion, one hundred eleven billion, one hundred ten million, twenty-one thousand, nine hundred sixty-one".