18817548521 has 4 divisors (see below), whose sum is σ = 18822930000. Its totient is φ = 18812167044.

The previous prime is 18817548499. The next prime is 18817548527. The reversal of 18817548521 is 12584571881.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12584571881 = 7 ⋅1797795983.

It is a cyclic number.

It is not a de Polignac number, because 18817548521 - 2²⁶ = 18750439657 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18817548521.

It is not an unprimeable number, because it can be changed into a prime (18817548527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2685491 + ... + 2692488.

It is an arithmetic number, because the mean of its divisors is an integer number (4705732500).

Almost surely, 2^18817548521 is an apocalyptic number.

It is an amenable number.

18817548521 is a deficient number, since it is larger than the sum of its proper divisors (5381479).

18817548521 is an equidigital number, since it uses as much as digits as its factorization.

18817548521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5381478.

The product of its digits is 716800, while the sum is 50.

The spelling of 18817548521 in words is "eighteen billion, eight hundred seventeen million, five hundred forty-eight thousand, five hundred twenty-one".