866644 has 6 divisors (see below), whose sum is σ = 1516634. Its totient is φ = 433320.

The previous prime is 866641. The next prime is 866653. The reversal of 866644 is 446668.

866644 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 810000 + 56644 = 900^2 + 238^2 .

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108327 + ... + 108334.

2⁸⁶⁶⁶⁴⁴ is an apocalyptic number.

It is an amenable number.

866644 is a deficient number, since it is larger than the sum of its proper divisors (649990).

866644 is a wasteful number, since it uses less digits than its factorization.

866644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216665 (or 216663 counting only the distinct ones).

The product of its digits is 27648, while the sum is 34.

The square root of 866644 is about 930.9371622188. The cubic root of 866644 is about 95.3411190060.

It can be divided in two parts, 86664 and 4, that added together give a palindrome (86668).

The spelling of 866644 in words is "eight hundred sixty-six thousand, six hundred forty-four".