866189981 has 8 divisors (see below), whose sum is σ = 870923520. Its totient is φ = 861465168.

The previous prime is 866189963. The next prime is 866189999. The reversal of 866189981 is 189981668.

It is an interprime number because it is at equal distance from previous prime (866189963) and next prime (866189999).

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

It is a cyclic number.

It is not a de Polignac number, because 866189981 - 2²² = 861995677 is a prime.

It is a super-2 number, since 2×866189981² = 1500570166369560722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866189581) 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 7 ways as a sum of consecutive naturals, for example, 311660 + ... + 314426.

It is an arithmetic number, because the mean of its divisors is an integer number (108865440).

Almost surely, 2^866189981 is an apocalyptic number.

It is an amenable number.

866189981 is a deficient number, since it is larger than the sum of its proper divisors (4733539).

866189981 is a wasteful number, since it uses less digits than its factorization.

866189981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4363.

The product of its digits is 1492992, while the sum is 56.

The square root of 866189981 is about 29431.1056707015. The cubic root of 866189981 is about 953.2446693939.

The spelling of 866189981 in words is "eight hundred sixty-six million, one hundred eighty-nine thousand, nine hundred eighty-one".