866631 has 4 divisors (see below), whose sum is σ = 1155512. Its totient is φ = 577752.

The previous prime is 866629. The next prime is 866639. The reversal of 866631 is 136668.

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

It is not a de Polignac number, because 866631 - 2¹ = 866629 is a prime.

It is a super-2 number, since 2×866631² = 1502098580322, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a plaindrome in base 13.

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 (866639) 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, 144436 + ... + 144441.

It is an arithmetic number, because the mean of its divisors is an integer number (288878).

2⁸⁶⁶⁶³¹ is an apocalyptic number.

866631 is a deficient number, since it is larger than the sum of its proper divisors (288881).

866631 is a wasteful number, since it uses less digits than its factorization.

866631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288880.

The product of its digits is 5184, while the sum is 30.

The square root of 866631 is about 930.9301799813. The cubic root of 866631 is about 95.3406422855.

The spelling of 866631 in words is "eight hundred sixty-six thousand, six hundred thirty-one".