856821888 has 288 divisors, whose sum is σ = 2785713840. Its totient is φ = 262020096.

The previous prime is 856821887. The next prime is 856821893. The reversal of 856821888 is 888128658.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (288).

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

It is not an unprimeable number, because it can be changed into a prime (856821881) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 5256495 + ... + 5256657.

Almost surely, 2^856821888 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 856821888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1392856920).

856821888 is an abundant number, since it is smaller than the sum of its proper divisors (1928891952).

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

856821888 is a wasteful number, since it uses less digits than its factorization.

856821888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218 (or 181 counting only the distinct ones).

The product of its digits is 1966080, while the sum is 54.

The square root of 856821888 is about 29271.5200835215. The cubic root of 856821888 is about 949.7956672265.

The spelling of 856821888 in words is "eight hundred fifty-six million, eight hundred twenty-one thousand, eight hundred eighty-eight".