856641440 has 144 divisors (see below), whose sum is σ = 2194857000. Its totient is φ = 315549696.

The previous prime is 856641403. The next prime is 856641479. The reversal of 856641440 is 44146658.

856641440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 766846864 + 89794576 = 27692^2 + 9476^2 .

It is a junction number, because it is equal to n+sod(n) for n = 856641394 and 856641403.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2454386 + ... + 2454734.

Almost surely, 2^856641440 is an apocalyptic number.

856641440 is a gapful number since it is divisible by the number (80) 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 856641440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1097428500).

856641440 is an abundant number, since it is smaller than the sum of its proper divisors (1338215560).

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

856641440 is a wasteful number, since it uses less digits than its factorization.

856641440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 439 (or 408 counting only the distinct ones).

The product of its (nonzero) digits is 92160, while the sum is 38.

The square root of 856641440 is about 29268.4376077713. The cubic root of 856641440 is about 949.7289864052.

The spelling of 856641440 in words is "eight hundred fifty-six million, six hundred forty-one thousand, four hundred forty".