866581872 has 80 divisors (see below), whose sum is σ = 2433594240. Its totient is φ = 264128256.

The previous prime is 866581861. The next prime is 866581883. The reversal of 866581872 is 278185668.

It is an interprime number because it is at equal distance from previous prime (866581861) and next prime (866581883).

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60279 + ... + 73257.

It is an arithmetic number, because the mean of its divisors is an integer number (30419928).

Almost surely, 2^866581872 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 866581872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1216797120).

866581872 is an abundant number, since it is smaller than the sum of its proper divisors (1567012368).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

866581872 is a wasteful number, since it uses less digits than its factorization.

866581872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13110 (or 13104 counting only the distinct ones).

The product of its digits is 1290240, while the sum is 51.

The square root of 866581872 is about 29437.7626867260. The cubic root of 866581872 is about 953.3884067922.

The spelling of 866581872 in words is "eight hundred sixty-six million, five hundred eighty-one thousand, eight hundred seventy-two".