111131981 has 2 divisors, whose sum is σ = 111131982. Its totient is φ = 111131980.

The previous prime is 111131963. The next prime is 111132001. The reversal of 111131981 is 189131111.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 102191881 + 8940100 = 10109^2 + 2990^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-111131981 is a prime.

It is a super-2 number, since 2×111131981² = 24700634401968722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 111131981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111136981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55565990 + 55565991.

It is an arithmetic number, because the mean of its divisors is an integer number (55565991).

Almost surely, 2^111131981 is an apocalyptic number.

It is an amenable number.

111131981 is a deficient number, since it is larger than the sum of its proper divisors (1).

111131981 is an equidigital number, since it uses as much as digits as its factorization.

111131981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216, while the sum is 26.

The square root of 111131981 is about 10541.9154331649. The cubic root of 111131981 is about 480.7799544731.

The spelling of 111131981 in words is "one hundred eleven million, one hundred thirty-one thousand, nine hundred eighty-one".