865009 has 4 divisors (see below), whose sum is σ = 866880. Its totient is φ = 863140.

The previous prime is 865003. The next prime is 865043. The reversal of 865009 is 900568.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 865009 - 2³ = 865001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (865001) 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 3 ways as a sum of consecutive naturals, for example, 324 + ... + 1354.

It is an arithmetic number, because the mean of its divisors is an integer number (216720).

2⁸⁶⁵⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

865009 is a deficient number, since it is larger than the sum of its proper divisors (1871).

865009 is a wasteful number, since it uses less digits than its factorization.

865009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1870.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 865009 is about 930.0586003043. The cubic root of 865009 is about 95.2811247979.

The spelling of 865009 in words is "eight hundred sixty-five thousand, nine".