9981720720 has 240 divisors, whose sum is σ = 35574931392. Its totient is φ = 2599672320.

The previous prime is 9981720691. The next prime is 9981720751. The reversal of 9981720720 is 270271899.

It is a tau number, because it is divible by the number of its divisors (240).

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 47 ways as a sum of consecutive naturals, for example, 829950 + ... + 841890.

Almost surely, 2^9981720720 is an apocalyptic number.

9981720720 is a gapful number since it is divisible by the number (90) 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 9981720720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17787465696).

9981720720 is an abundant number, since it is smaller than the sum of its proper divisors (25593210672).

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

9981720720 is a wasteful number, since it uses less digits than its factorization.

9981720720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12012 (or 11994 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 9981720720 is about 99908.5617952736. The cubic root of 9981720720 is about 2153.1211722031.

The spelling of 9981720720 in words is "nine billion, nine hundred eighty-one million, seven hundred twenty thousand, seven hundred twenty".