8661591988 has 24 divisors (see below), whose sum is σ = 18076367232. Its totient is φ = 3550714464.

The previous prime is 8661591979. The next prime is 8661592003. The reversal of 8661591988 is 8891951668.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6724195 + ... + 6725482.

It is an arithmetic number, because the mean of its divisors is an integer number (753181968).

Almost surely, 2^8661591988 is an apocalyptic number.

It is an amenable number.

8661591988 is an abundant number, since it is smaller than the sum of its proper divisors (9414775244).

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

8661591988 is a wasteful number, since it uses less digits than its factorization.

8661591988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13449711 (or 13449709 counting only the distinct ones).

The product of its digits is 7464960, while the sum is 61.

The square root of 8661591988 is about 93067.6742376213. The cubic root of 8661591988 is about 2053.6790557349.

The spelling of 8661591988 in words is "eight billion, six hundred sixty-one million, five hundred ninety-one thousand, nine hundred eighty-eight".