866643 has 8 divisors (see below), whose sum is σ = 1223568. Its totient is φ = 543744.

The previous prime is 866641. The next prime is 866653. The reversal of 866643 is 346668.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 866643 - 2¹ = 866641 is a prime.

It is a super-4 number, since 4×866643⁴ (a number of 25 digits) contains 4444 as substring.

866643 is a lucky number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (866641) 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 7 ways as a sum of consecutive naturals, for example, 8446 + ... + 8547.

It is an arithmetic number, because the mean of its divisors is an integer number (152946).

2⁸⁶⁶⁶⁴³ is an apocalyptic number.

866643 is a deficient number, since it is larger than the sum of its proper divisors (356925).

866643 is a wasteful number, since it uses less digits than its factorization.

866643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17013.

The product of its digits is 20736, while the sum is 33.

The square root of 866643 is about 930.9366251255. The cubic root of 866643 is about 95.3410823353.

The spelling of 866643 in words is "eight hundred sixty-six thousand, six hundred forty-three".