18531521817 has 16 divisors (see below), whose sum is σ = 25995443712. Its totient is φ = 11727262080.

The previous prime is 18531521791. The next prime is 18531521821. The reversal of 18531521817 is 71812513581.

It is not a de Polignac number, because 18531521817 - 2⁶ = 18531521753 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18531521867) 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, 2031433 + ... + 2040534.

It is an arithmetic number, because the mean of its divisors is an integer number (1624715232).

Almost surely, 2^18531521817 is an apocalyptic number.

It is an amenable number.

18531521817 is a deficient number, since it is larger than the sum of its proper divisors (7463921895).

18531521817 is a wasteful number, since it uses less digits than its factorization.

18531521817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4072048.

The product of its digits is 67200, while the sum is 42.

The spelling of 18531521817 in words is "eighteen billion, five hundred thirty-one million, five hundred twenty-one thousand, eight hundred seventeen".