866321 has 4 divisors (see below), whose sum is σ = 886512. Its totient is φ = 846132.

The previous prime is 866311. The next prime is 866329. The reversal of 866321 is 123668.

866321 = 9² + 10² + ... + 137².

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 a de Polignac number, because none of the positive numbers 2^k-866321 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (866329) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10031 + ... + 10116.

It is an arithmetic number, because the mean of its divisors is an integer number (221628).

2⁸⁶⁶³²¹ is an apocalyptic number.

It is an amenable number.

866321 is a deficient number, since it is larger than the sum of its proper divisors (20191).

866321 is a wasteful number, since it uses less digits than its factorization.

866321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20190.

The product of its digits is 1728, while the sum is 26.

The square root of 866321 is about 930.7636649548. The cubic root of 866321 is about 95.3292729238.

Adding to 866321 its reverse (123668), we get a palindrome (989989).

The spelling of 866321 in words is "eight hundred sixty-six thousand, three hundred twenty-one".