866840 has 32 divisors (see below), whose sum is σ = 2101680. Its totient is φ = 319872.

The previous prime is 866819. The next prime is 866843. The reversal of 866840 is 48668.

866840 = 62² + 63² + ... + 141².

It is a junction number, because it is equal to n+sod(n) for n = 866797 and 866806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866843) by changing a digit.

866840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 314 + ... + 1353.

2⁸⁶⁶⁸⁴⁰ is an apocalyptic number.

It is an amenable number.

866840 is an abundant number, since it is smaller than the sum of its proper divisors (1234840).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

866840 is a wasteful number, since it uses less digits than its factorization.

866840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1691 (or 1687 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 866840 is about 931.0424265306. The cubic root of 866840 is about 95.3483059058.

The spelling of 866840 in words is "eight hundred sixty-six thousand, eight hundred forty".