866531 has 4 divisors (see below), whose sum is σ = 868512. Its totient is φ = 864552.

The previous prime is 866519. The next prime is 866573. The reversal of 866531 is 135668.

866531 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 866531 - 2¹⁴ = 850147 is a prime.

It is a super-2 number, since 2×866531² = 1501751947922, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 866494 and 866503.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 866531.

It is not an unprimeable number, because it can be changed into a prime (866581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11 + ... + 1316.

It is an arithmetic number, because the mean of its divisors is an integer number (217128).

2⁸⁶⁶⁵³¹ is an apocalyptic number.

866531 is a deficient number, since it is larger than the sum of its proper divisors (1981).

866531 is a wasteful number, since it uses less digits than its factorization.

866531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1980.

The product of its digits is 4320, while the sum is 29.

The square root of 866531 is about 930.8764687111. The cubic root of 866531 is about 95.3369750458.

The spelling of 866531 in words is "eight hundred sixty-six thousand, five hundred thirty-one".