856891 has 8 divisors (see below), whose sum is σ = 986624. Its totient is φ = 729000.

The previous prime is 856853. The next prime is 856897. The reversal of 856891 is 198658.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 3-Lehmer number, since φ(856891) divides (856891-1)³.

It is a cyclic number.

It is not a de Polignac number, because 856891 - 2¹³ = 848699 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 856891.

It is not an unprimeable number, because it can be changed into a prime (856897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 766 + ... + 1516.

It is an arithmetic number, because the mean of its divisors is an integer number (123328).

2⁸⁵⁶⁸⁹¹ is an apocalyptic number.

856891 is a deficient number, since it is larger than the sum of its proper divisors (129733).

856891 is a wasteful number, since it uses less digits than its factorization.

856891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 921.

The product of its digits is 17280, while the sum is 37.

The square root of 856891 is about 925.6840713764. The cubic root of 856891 is about 94.9821203655.

The spelling of 856891 in words is "eight hundred fifty-six thousand, eight hundred ninety-one".