8921565720 has 128 divisors (see below), whose sum is σ = 29938680000. Its totient is φ = 2363074560.

The previous prime is 8921565701. The next prime is 8921565721. The reversal of 8921565720 is 275651298.

8921565720 is a `hidden beast` number, since 8 + 9 + 21 + 56 + 572 + 0 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8921565721) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 133200 + ... + 188640.

Almost surely, 2^8921565720 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 8921565720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14969340000).

8921565720 is an abundant number, since it is smaller than the sum of its proper divisors (21017114280).

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

8921565720 is a wasteful number, since it uses less digits than its factorization.

8921565720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55610 (or 55600 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The square root of 8921565720 is about 94454.0402523894. The cubic root of 8921565720 is about 2074.0235959731.

The spelling of 8921565720 in words is "eight billion, nine hundred twenty-one million, five hundred sixty-five thousand, seven hundred twenty".