856839 has 4 divisors (see below), whose sum is σ = 1142456. Its totient is φ = 571224.

The previous prime is 856831. The next prime is 856841. The reversal of 856839 is 938658.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 856839 - 2³ = 856831 is a prime.

It is a D-number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 856797 and 856806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (856831) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 142804 + ... + 142809.

It is an arithmetic number, because the mean of its divisors is an integer number (285614).

2⁸⁵⁶⁸³⁹ is an apocalyptic number.

856839 is a deficient number, since it is larger than the sum of its proper divisors (285617).

856839 is a wasteful number, since it uses less digits than its factorization.

856839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285616.

The product of its digits is 51840, while the sum is 39.

The square root of 856839 is about 925.6559836138. The cubic root of 856839 is about 94.9801990126.

The spelling of 856839 in words is "eight hundred fifty-six thousand, eight hundred thirty-nine".