18188561664 has 972 divisors, whose sum is σ = 72232979364. Its totient is φ = 4514807808.

The previous prime is 18188561653. The next prime is 18188561683. The reversal of 18188561664 is 46616588181.

18188561664 is a `hidden beast` number, since 1 + 8 + 18 + 8 + 5 + 616 + 6 + 4 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 8230118400 + 9958443264 = 90720^2 + 99792^2 .

It is a tau number, because it is divible by the number of its divisors (972).

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

It is a self number, because there is not a number n which added to its sum of digits gives 18188561664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 1069915384 + ... + 1069915400.

Almost surely, 2^18188561664 is an apocalyptic number.

18188561664 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18188561664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36116489682).

18188561664 is an abundant number, since it is smaller than the sum of its proper divisors (54044417700).

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

18188561664 is an frugal number, since it uses more digits than its factorization.

18188561664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84 (or 42 counting only the distinct ones).

The product of its digits is 2211840, while the sum is 54.

The spelling of 18188561664 in words is "eighteen billion, one hundred eighty-eight million, five hundred sixty-one thousand, six hundred sixty-four".