865861 has 12 divisors (see below), whose sum is σ = 965196. Its totient is φ = 773760.

The previous prime is 865859. The next prime is 865867. The reversal of 865861 is 168568.

It is a happy number.

865861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 649636 + 216225 = 806^2 + 465^2 .

It is not a de Polignac number, because 865861 - 2¹ = 865859 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 (865867) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16311 + ... + 16363.

It is an arithmetic number, because the mean of its divisors is an integer number (80433).

2⁸⁶⁵⁸⁶¹ is an apocalyptic number.

It is an amenable number.

865861 is a deficient number, since it is larger than the sum of its proper divisors (99335).

865861 is a wasteful number, since it uses less digits than its factorization.

865861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132 (or 101 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 865861 is about 930.5165232278. The cubic root of 865861 is about 95.3123972587.

The spelling of 865861 in words is "eight hundred sixty-five thousand, eight hundred sixty-one".