18597775921 has 4 divisors (see below), whose sum is σ = 18600075252. Its totient is φ = 18595476592.

The previous prime is 18597775913. The next prime is 18597775927. The reversal of 18597775921 is 12957779581.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17459658225 + 1138117696 = 132135^2 + 33736^2 .

It is a cyclic number.

It is not a de Polignac number, because 18597775921 - 2³ = 18597775913 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 18597775921.

It is not an unprimeable number, because it can be changed into a prime (18597775927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1137490 + ... + 1153723.

It is an arithmetic number, because the mean of its divisors is an integer number (4650018813).

Almost surely, 2^18597775921 is an apocalyptic number.

It is an amenable number.

18597775921 is a deficient number, since it is larger than the sum of its proper divisors (2299331).

18597775921 is an equidigital number, since it uses as much as digits as its factorization.

18597775921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2299330.

The product of its digits is 11113200, while the sum is 61.

The spelling of 18597775921 in words is "eighteen billion, five hundred ninety-seven million, seven hundred seventy-five thousand, nine hundred twenty-one".