865921 has 8 divisors (see below), whose sum is σ = 1000064. Its totient is φ = 734400.

The previous prime is 865889. The next prime is 865933. The reversal of 865921 is 129568.

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 865921 - 2⁵ = 865889 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (865121) 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, 121 + ... + 1321.

It is an arithmetic number, because the mean of its divisors is an integer number (125008).

2⁸⁶⁵⁹²¹ is an apocalyptic number.

It is an amenable number.

865921 is a deficient number, since it is larger than the sum of its proper divisors (134143).

865921 is a wasteful number, since it uses less digits than its factorization.

865921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1311.

The product of its digits is 4320, while the sum is 31.

The square root of 865921 is about 930.5487628276. The cubic root of 865921 is about 95.3145987713.

The spelling of 865921 in words is "eight hundred sixty-five thousand, nine hundred twenty-one".