8491661568 has 540 divisors, whose sum is σ = 29232460180. Its totient is φ = 2436562944.

The previous prime is 8491661513. The next prime is 8491661603. The reversal of 8491661568 is 8651661948.

8491661568 is a `hidden beast` number, since 8 + 4 + 9 + 16 + 61 + 568 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 339738624 + 8151922944 = 18432^2 + 90288^2 .

It is a Harshad number since it is a multiple of its sum of digits (54).

Its product of digits (2488320) is a multiple of the sum of its prime divisors (144).

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 77905098 + ... + 77905206.

Almost surely, 2^8491661568 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 8491661568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14616230090).

8491661568 is an abundant number, since it is smaller than the sum of its proper divisors (20740798612).

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

8491661568 is a wasteful number, since it uses less digits than its factorization.

8491661568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184 (or 144 counting only the distinct ones).

The product of its digits is 2488320, while the sum is 54.

The square root of 8491661568 is about 92150.2119802228. The cubic root of 8491661568 is about 2040.1599874526.

The spelling of 8491661568 in words is "eight billion, four hundred ninety-one million, six hundred sixty-one thousand, five hundred sixty-eight".