1111171981 has 2 divisors, whose sum is σ = 1111171982. Its totient is φ = 1111171980.

The previous prime is 1111171973. The next prime is 1111171993. The reversal of 1111171981 is 1891711111.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 709369956 + 401802025 = 26634^2 + 20045^2 .

It is a cyclic number.

It is not a de Polignac number, because 1111171981 - 2³ = 1111171973 is a prime.

It is a super-3 number, since 3×1111171981³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1111171951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 555585990 + 555585991.

It is an arithmetic number, because the mean of its divisors is an integer number (555585991).

Almost surely, 2^1111171981 is an apocalyptic number.

It is an amenable number.

1111171981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1111171981 is an equidigital number, since it uses as much as digits as its factorization.

1111171981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 504, while the sum is 31.

The square root of 1111171981 is about 33334.2463691622. The cubic root of 1111171981 is about 1035.7630819957.

The spelling of 1111171981 in words is "one billion, one hundred eleven million, one hundred seventy-one thousand, nine hundred eighty-one".