811865 has 8 divisors (see below), whose sum is σ = 979080. Its totient is φ = 646272.

The previous prime is 811861. The next prime is 811871. The reversal of 811865 is 568118.

811865 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 4 ways, for example, as 299209 + 512656 = 547^2 + 716^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 811865 - 2² = 811861 is a prime.

It is not an unprimeable number, because it can be changed into a prime (811861) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1781 + ... + 2189.

It is an arithmetic number, because the mean of its divisors is an integer number (122385).

2⁸¹¹⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

811865 is a deficient number, since it is larger than the sum of its proper divisors (167215).

811865 is a wasteful number, since it uses less digits than its factorization.

811865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 811.

The product of its digits is 1920, while the sum is 29.

The square root of 811865 is about 901.0355153933. The cubic root of 811865 is about 93.2884634096.

The spelling of 811865 in words is "eight hundred eleven thousand, eight hundred sixty-five".