866440 has 16 divisors (see below), whose sum is σ = 1949580. Its totient is φ = 346560.

The previous prime is 866431. The next prime is 866443. The reversal of 866440 is 44668.

It can be written as a sum of positive squares in 2 ways, for example, as 842724 + 23716 = 918^2 + 154^2 .

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 866399 and 866408.

It is not an unprimeable number, because it can be changed into a prime (866443) 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, 10791 + ... + 10870.

2⁸⁶⁶⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

866440 is an abundant number, since it is smaller than the sum of its proper divisors (1083140).

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

866440 is a wasteful number, since it uses less digits than its factorization.

866440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21672 (or 21668 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 866440 is about 930.8275887617. The cubic root of 866440 is about 95.3336376124. Note that the first 3 decimals are identical.

The spelling of 866440 in words is "eight hundred sixty-six thousand, four hundred forty".