8640865440 has 144 divisors (see below), whose sum is σ = 29547390600. Its totient is φ = 2299508736.

The previous prime is 8640865421. The next prime is 8640865483. The reversal of 8640865440 is 445680468.

It can be written as a sum of positive squares in 4 ways, for example, as 5866947216 + 2773918224 = 76596^2 + 52668^2 .

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 727066 + ... + 738854.

Almost surely, 2^8640865440 is an apocalyptic number.

8640865440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8640865440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14773695300).

8640865440 is an abundant number, since it is smaller than the sum of its proper divisors (20906525160).

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

8640865440 is a wasteful number, since it uses less digits than its factorization.

8640865440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12319 (or 12308 counting only the distinct ones).

The product of its (nonzero) digits is 737280, while the sum is 45.

The square root of 8640865440 is about 92956.2555183889. The cubic root of 8640865440 is about 2052.0396467609.

The spelling of 8640865440 in words is "eight billion, six hundred forty million, eight hundred sixty-five thousand, four hundred forty".