18561856320 has 560 divisors, whose sum is σ = 75950844288. Its totient is φ = 4232632320.

The previous prime is 18561856273. The next prime is 18561856321. The reversal of 18561856320 is 2365816581.

18561856320 is a `hidden beast` number, since 1 + 8 + 5 + 6 + 1 + 8 + 5 + 632 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (560).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18561856321) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 44089710 + ... + 44090130.

Almost surely, 2^18561856320 is an apocalyptic number.

18561856320 is a gapful number since it is divisible by the number (10) 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 18561856320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37975422144).

18561856320 is an abundant number, since it is smaller than the sum of its proper divisors (57388987968).

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

18561856320 is an frugal number, since it uses more digits than its factorization.

18561856320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 472 (or 438 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

The spelling of 18561856320 in words is "eighteen billion, five hundred sixty-one million, eight hundred fifty-six thousand, three hundred twenty".