8661978720 has 288 divisors, whose sum is σ = 31421688480. Its totient is φ = 2165391360.

The previous prime is 8661978713. The next prime is 8661978749. The reversal of 8661978720 is 278791668.

It is a tau number, because it is divible by the number of its divisors (288).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8102346 + ... + 8103414.

It is an arithmetic number, because the mean of its divisors is an integer number (109103085).

Almost surely, 2^8661978720 is an apocalyptic number.

8661978720 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 8661978720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15710844240).

8661978720 is an abundant number, since it is smaller than the sum of its proper divisors (22759709760).

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

8661978720 is a wasteful number, since it uses less digits than its factorization.

8661978720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1438 (or 1427 counting only the distinct ones).

The product of its (nonzero) digits is 2032128, while the sum is 54.

The square root of 8661978720 is about 93069.7519068360. The cubic root of 8661978720 is about 2053.7096202312.

The spelling of 8661978720 in words is "eight billion, six hundred sixty-one million, nine hundred seventy-eight thousand, seven hundred twenty".