866681 has 4 divisors (see below), whose sum is σ = 875364. Its totient is φ = 858000.

The previous prime is 866653. The next prime is 866683. The reversal of 866681 is 186668.

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 354025 + 512656 = 595^2 + 716^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-866681 is a prime.

It is a super-2 number, since 2×866681² = 1502271911522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (866683) 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, 4190 + ... + 4391.

It is an arithmetic number, because the mean of its divisors is an integer number (218841).

2⁸⁶⁶⁶⁸¹ is an apocalyptic number.

It is an amenable number.

866681 is a deficient number, since it is larger than the sum of its proper divisors (8683).

866681 is a wasteful number, since it uses less digits than its factorization.

866681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8682.

The product of its digits is 13824, while the sum is 35.

The square root of 866681 is about 930.9570344543. The cubic root of 866681 is about 95.3424757996.

The spelling of 866681 in words is "eight hundred sixty-six thousand, six hundred eighty-one".