11112121111981 has 2 divisors, whose sum is σ = 11112121111982. Its totient is φ = 11112121111980.

The previous prime is 11112121111979. The next prime is 11112121112021. The reversal of 11112121111981 is 18911112121111.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6677748529956 + 4434372582025 = 2584134^2 + 2105795^2 .

It is a cyclic number.

It is not a de Polignac number, because 11112121111981 - 2¹ = 11112121111979 is a prime.

It is a super-2 number, since 2×11112121111981² (a number of 27 digits) contains 22 as substring.

Together with 11112121111979, 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 (11112121111921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5556060555990 + 5556060555991.

It is an arithmetic number, because the mean of its divisors is an integer number (5556060555991).

Almost surely, 2^{11112121111981} is an apocalyptic number.

It is an amenable number.

11112121111981 is a deficient number, since it is larger than the sum of its proper divisors (1).

11112121111981 is an equidigital number, since it uses as much as digits as its factorization.

11112121111981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 31.

The spelling of 11112121111981 in words is "eleven trillion, one hundred twelve billion, one hundred twenty-one million, one hundred eleven thousand, nine hundred eighty-one".