18040913981 has 2 divisors, whose sum is σ = 18040913982. Its totient is φ = 18040913980.

The previous prime is 18040913971. The next prime is 18040914053. The reversal of 18040913981 is 18931904081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10767382756 + 7273531225 = 103766^2 + 85285^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18040913981 is a prime.

It is a super-2 number, since 2×18040913981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18040913971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9020456990 + 9020456991.

It is an arithmetic number, because the mean of its divisors is an integer number (9020456991).

Almost surely, 2^18040913981 is an apocalyptic number.

It is an amenable number.

18040913981 is a deficient number, since it is larger than the sum of its proper divisors (1).

18040913981 is an equidigital number, since it uses as much as digits as its factorization.

18040913981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 44.

The spelling of 18040913981 in words is "eighteen billion, forty million, nine hundred thirteen thousand, nine hundred eighty-one".