18391490856 has 128 divisors (see below), whose sum is σ = 52043904000. Its totient is φ = 6016095936.

The previous prime is 18391490839. The next prime is 18391490881. The reversal of 18391490856 is 65809419381.

18391490856 is a `hidden beast` number, since 18 + 3 + 91 + 490 + 8 + 56 = 666.

It is a super-2 number, since 2×18391490856² (a number of 21 digits) contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11303115 + ... + 11304741.

It is an arithmetic number, because the mean of its divisors is an integer number (406593000).

Almost surely, 2^18391490856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18391490856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26021952000).

18391490856 is an abundant number, since it is smaller than the sum of its proper divisors (33652413144).

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

18391490856 is a wasteful number, since it uses less digits than its factorization.

18391490856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2588 (or 2578 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 54.

The spelling of 18391490856 in words is "eighteen billion, three hundred ninety-one million, four hundred ninety thousand, eight hundred fifty-six".