1011111121981 has 2 divisors, whose sum is σ = 1011111121982. Its totient is φ = 1011111121980.

The previous prime is 1011111121939. The next prime is 1011111122027. The reversal of 1011111121981 is 1891211111101.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 859762890756 + 151348231225 = 927234^2 + 389035^2 .

It is a cyclic number.

It is not a de Polignac number, because 1011111121981 - 2²³ = 1011102733373 is a prime.

It is a super-2 number, since 2×1011111121981² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1011111121901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 505555560990 + 505555560991.

It is an arithmetic number, because the mean of its divisors is an integer number (505555560991).

Almost surely, 2^{1011111121981} is an apocalyptic number.

It is an amenable number.

1011111121981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1011111121981 is an equidigital number, since it uses as much as digits as its factorization.

1011111121981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 28.

The spelling of 1011111121981 in words is "one trillion, eleven billion, one hundred eleven million, one hundred twenty-one thousand, nine hundred eighty-one".