18512664981 has 8 divisors (see below), whose sum is σ = 26135527104. Its totient is φ = 11615789760.

The previous prime is 18512664959. The next prime is 18512665019. The reversal of 18512664981 is 18946621581.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18512664981 - 2²⁷ = 18378447253 is a prime.

It is a super-2 number, since 2×18512664981² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (51), and also a Moran number because the ratio is a prime number: 362993431 = 18512664981 / (1 + 8 + 5 + 1 + 2 + 6 + 6 + 4 + 9 + 8 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18512664941) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 181496665 + ... + 181496766.

It is an arithmetic number, because the mean of its divisors is an integer number (3266940888).

Almost surely, 2^18512664981 is an apocalyptic number.

It is an amenable number.

18512664981 is a deficient number, since it is larger than the sum of its proper divisors (7622862123).

18512664981 is a wasteful number, since it uses less digits than its factorization.

18512664981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362993451.

The product of its digits is 829440, while the sum is 51.

The spelling of 18512664981 in words is "eighteen billion, five hundred twelve million, six hundred sixty-four thousand, nine hundred eighty-one".