866391 has 8 divisors (see below), whose sum is σ = 1177200. Its totient is φ = 566592.

The previous prime is 866389. The next prime is 866399. The reversal of 866391 is 193668.

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

It is not a de Polignac number, because 866391 - 2¹ = 866389 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 866391.

It is not an unprimeable number, because it can be changed into a prime (866399) 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 7 ways as a sum of consecutive naturals, for example, 2566 + ... + 2883.

It is an arithmetic number, because the mean of its divisors is an integer number (147150).

2⁸⁶⁶³⁹¹ is an apocalyptic number.

866391 is a deficient number, since it is larger than the sum of its proper divisors (310809).

866391 is a wasteful number, since it uses less digits than its factorization.

866391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5505.

The product of its digits is 7776, while the sum is 33.

The square root of 866391 is about 930.8012677258. The cubic root of 866391 is about 95.3318404361.

The spelling of 866391 in words is "eight hundred sixty-six thousand, three hundred ninety-one".