866557 has 4 divisors (see below), whose sum is σ = 871740. Its totient is φ = 861376.

The previous prime is 866519. The next prime is 866573. The reversal of 866557 is 755668.

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 622521 + 244036 = 789^2 + 494^2 .

It is a cyclic number.

It is not a de Polignac number, because 866557 - 2¹¹ = 864509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866057) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2332 + ... + 2677.

It is an arithmetic number, because the mean of its divisors is an integer number (217935).

2⁸⁶⁶⁵⁵⁷ is an apocalyptic number.

It is an amenable number.

866557 is a deficient number, since it is larger than the sum of its proper divisors (5183).

866557 is a wasteful number, since it uses less digits than its factorization.

866557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5182.

The product of its digits is 50400, while the sum is 37.

The square root of 866557 is about 930.8904339395. The cubic root of 866557 is about 95.3379285552.

Subtracting from 866557 its reverse (755668), we obtain a square (110889 = 333²).

The spelling of 866557 in words is "eight hundred sixty-six thousand, five hundred fifty-seven".