856591 has 4 divisors (see below), whose sum is σ = 860112. Its totient is φ = 853072.

The previous prime is 856571. The next prime is 856627. The reversal of 856591 is 195658.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 195658 = 2 ⋅97829.

It is a cyclic number.

It is not a de Polignac number, because 856591 - 2¹³ = 848399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (856571) 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, 1366 + ... + 1891.

It is an arithmetic number, because the mean of its divisors is an integer number (215028).

2⁸⁵⁶⁵⁹¹ is an apocalyptic number.

856591 is a deficient number, since it is larger than the sum of its proper divisors (3521).

856591 is a wasteful number, since it uses less digits than its factorization.

856591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3520.

The product of its digits is 10800, while the sum is 34.

The square root of 856591 is about 925.5220148651. The cubic root of 856591 is about 94.9710345673.

The spelling of 856591 in words is "eight hundred fifty-six thousand, five hundred ninety-one".