18991044864 has 567 divisors, whose sum is σ = 64700979889. Its totient is φ = 5556418560.

The previous prime is 18991044857. The next prime is 18991044889. The reversal of 18991044864 is 46844019981.

It is a happy number.

The square root of 18991044864 is 137808.

It is a perfect power (a square), and thus also a powerful number.

18991044864 is a `hidden beast` number, since 189 + 9 + 10 + 448 + 6 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 9958443264 + 9032601600 = 99792^2 + 95040^2 .

It is a super-3 number, since 3×18991044864³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

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 18991044864.

It is an unprimeable number.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 654863602 + ... + 654863630.

Almost surely, 2^18991044864 is an apocalyptic number.

18991044864 is the 137808-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18991044864

18991044864 is an abundant number, since it is smaller than the sum of its proper divisors (45709935025).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18991044864 is an frugal number, since it uses more digits than its factorization.

18991044864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114 (or 45 counting only the distinct ones).

The product of its (nonzero) digits is 1990656, while the sum is 54.

The spelling of 18991044864 in words is "eighteen billion, nine hundred ninety-one million, forty-four thousand, eight hundred sixty-four".