18538892821 has 4 divisors (see below), whose sum is σ = 18572785312. Its totient is φ = 18505000332.

The previous prime is 18538892807. The next prime is 18538892861. The reversal of 18538892821 is 12829883581.

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: 12829883581 = 1723 ⋅7446247.

It is a cyclic number.

It is not a de Polignac number, because 18538892821 - 2¹³ = 18538884629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18538892861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16945425 + ... + 16946518.

It is an arithmetic number, because the mean of its divisors is an integer number (4643196328).

Almost surely, 2^18538892821 is an apocalyptic number.

It is an amenable number.

18538892821 is a deficient number, since it is larger than the sum of its proper divisors (33892491).

18538892821 is an equidigital number, since it uses as much as digits as its factorization.

18538892821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33892490.

The product of its digits is 2211840, while the sum is 55.

The spelling of 18538892821 in words is "eighteen billion, five hundred thirty-eight million, eight hundred ninety-two thousand, eight hundred twenty-one".