18026115561 has 6 divisors (see below), whose sum is σ = 26037722490. Its totient is φ = 12017410368.

The previous prime is 18026115553. The next prime is 18026115607. The reversal of 18026115561 is 16551162081.

18026115561 is a `hidden beast` number, since 1 + 80 + 2 + 6 + 1 + 15 + 561 = 666.

It can be written as a sum of positive squares in only one way, i.e., 17284097961 + 742017600 = 131469^2 + 27240^2 .

It is not a de Polignac number, because 18026115561 - 2³ = 18026115553 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18026115661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1001450856 + ... + 1001450873.

It is an arithmetic number, because the mean of its divisors is an integer number (4339620415).

Almost surely, 2^18026115561 is an apocalyptic number.

It is an amenable number.

18026115561 is a deficient number, since it is larger than the sum of its proper divisors (8011606929).

18026115561 is a wasteful number, since it uses less digits than its factorization.

18026115561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2002901735 (or 2002901732 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 36.

The spelling of 18026115561 in words is "eighteen billion, twenty-six million, one hundred fifteen thousand, five hundred sixty-one".