856840 has 32 divisors (see below), whose sum is σ = 1992960. Its totient is φ = 331200.

The previous prime is 856831. The next prime is 856841. The reversal of 856840 is 48658.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is not an unprimeable number, because it can be changed into a prime (856841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 895 + ... + 1585.

It is an arithmetic number, because the mean of its divisors is an integer number (62280).

2⁸⁵⁶⁸⁴⁰ 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 856840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (996480).

856840 is an abundant number, since it is smaller than the sum of its proper divisors (1136120).

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

856840 is a wasteful number, since it uses less digits than its factorization.

856840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 733 (or 729 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 31.

The square root of 856840 is about 925.6565237711. The cubic root of 856840 is about 94.9802359624.

The spelling of 856840 in words is "eight hundred fifty-six thousand, eight hundred forty".