866385 has 24 divisors (see below), whose sum is σ = 1618344. Its totient is φ = 426240.

The previous prime is 866353. The next prime is 866389. The reversal of 866385 is 583668.

866385 = 8² + 9² + ... + 137².

It can be written as a sum of positive squares in 4 ways, for example, as 7056 + 859329 = 84^2 + 927^2 .

It is not a de Polignac number, because 866385 - 2⁵ = 866353 is a prime.

866385 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866389) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 156 + ... + 1325.

It is an arithmetic number, because the mean of its divisors is an integer number (67431).

2⁸⁶⁶³⁸⁵ is an apocalyptic number.

It is an amenable number.

866385 is a deficient number, since it is larger than the sum of its proper divisors (751959).

866385 is a wasteful number, since it uses less digits than its factorization.

866385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1505 (or 1502 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 866385 is about 930.7980446907. The cubic root of 866385 is about 95.3316203690.

The spelling of 866385 in words is "eight hundred sixty-six thousand, three hundred eighty-five".