866665 has 16 divisors (see below), whose sum is σ = 1108800. Its totient is φ = 649152.

The previous prime is 866653. The next prime is 866683. The reversal of 866665 is 566668.

It is a cyclic number.

It is not a de Polignac number, because 866665 - 2¹⁵ = 833897 is a prime.

It is a super-2 number, since 2×866665² = 1502216444450, which contains 22 as substring.

Its product of digits (51840) is a multiple of the sum of its prime divisors (216).

It is a nialpdrome in base 10.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 6166 + ... + 6304.

It is an arithmetic number, because the mean of its divisors is an integer number (69300).

2⁸⁶⁶⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

866665 is a deficient number, since it is larger than the sum of its proper divisors (242135).

866665 is a wasteful number, since it uses less digits than its factorization.

866665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216.

The product of its digits is 51840, while the sum is 37.

The square root of 866665 is about 930.9484411072. The cubic root of 866665 is about 95.3418890828.

The spelling of 866665 in words is "eight hundred sixty-six thousand, six hundred sixty-five".