865649 has 4 divisors (see below), whose sum is σ = 882036. Its totient is φ = 849264.

The previous prime is 865643. The next prime is 865661. The reversal of 865649 is 946568.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 313600 + 552049 = 560^2 + 743^2 .

It is a cyclic number.

It is not a de Polignac number, because 865649 - 2¹⁶ = 800113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (865643) 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, 8114 + ... + 8219.

It is an arithmetic number, because the mean of its divisors is an integer number (220509).

2⁸⁶⁵⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

865649 is a deficient number, since it is larger than the sum of its proper divisors (16387).

865649 is a wasteful number, since it uses less digits than its factorization.

865649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16386.

The product of its digits is 51840, while the sum is 38.

The square root of 865649 is about 930.4026010282. The cubic root of 865649 is about 95.3046177662.

The spelling of 865649 in words is "eight hundred sixty-five thousand, six hundred forty-nine".