865891 has 8 divisors (see below), whose sum is σ = 954800. Its totient is φ = 780192.

The previous prime is 865889. The next prime is 865933. The reversal of 865891 is 198568.

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

It is not a de Polignac number, because 865891 - 2¹ = 865889 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 865891.

It is not an unprimeable number, because it can be changed into a prime (865801) 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, 216 + ... + 1333.

It is an arithmetic number, because the mean of its divisors is an integer number (119350).

2⁸⁶⁵⁸⁹¹ is an apocalyptic number.

865891 is a deficient number, since it is larger than the sum of its proper divisors (88909).

865891 is a wasteful number, since it uses less digits than its factorization.

865891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1605.

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

The square root of 865891 is about 930.5326431673. The cubic root of 865891 is about 95.3134980277.

The spelling of 865891 in words is "eight hundred sixty-five thousand, eight hundred ninety-one".