18534643581 has 16 divisors (see below), whose sum is σ = 25405128000. Its totient is φ = 12010935168.

The previous prime is 18534643579. The next prime is 18534643607.

18534643581 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 18534643581 - 2¹ = 18534643579 is a prime.

It is a super-2 number, since 2×18534643581² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18534643581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18534643181) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36850 + ... + 196028.

It is an arithmetic number, because the mean of its divisors is an integer number (1587820500).

Almost surely, 2^18534643581 is an apocalyptic number.

It is an amenable number.

18534643581 is a deficient number, since it is larger than the sum of its proper divisors (6870484419).

18534643581 is a wasteful number, since it uses less digits than its factorization.

18534643581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160268.

The product of its digits is 1382400, while the sum is 48.

The spelling of 18534643581 in words is "eighteen billion, five hundred thirty-four million, six hundred forty-three thousand, five hundred eighty-one".