211121020021981 has 2 divisors, whose sum is σ = 211121020021982. Its totient is φ = 211121020021980.

The previous prime is 211121020021979. The next prime is 211121020022009. The reversal of 211121020021981 is 189120020121112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 129362189062500 + 81758830959481 = 11373750^2 + 9042059^2 .

It is a cyclic number.

It is not a de Polignac number, because 211121020021981 - 2¹ = 211121020021979 is a prime.

It is a super-2 number, since 2×211121020021981² (a number of 29 digits) contains 22 as substring.

Together with 211121020021979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211121020021381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105560510010990 + 105560510010991.

It is an arithmetic number, because the mean of its divisors is an integer number (105560510010991).

Almost surely, 2^{211121020021981} is an apocalyptic number.

It is an amenable number.

211121020021981 is a deficient number, since it is larger than the sum of its proper divisors (1).

211121020021981 is an equidigital number, since it uses as much as digits as its factorization.

211121020021981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 31.

The spelling of 211121020021981 in words is "two hundred eleven trillion, one hundred twenty-one billion, twenty million, twenty-one thousand, nine hundred eighty-one".