9867721728 has 88 divisors (see below), whose sum is σ = 26345184768. Its totient is φ = 3283726336.

The previous prime is 9867721727. The next prime is 9867721733. The reversal of 9867721728 is 8271277689.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9867721727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2095825 + ... + 2100527.

Almost surely, 2^9867721728 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 9867721728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13172592384).

9867721728 is an abundant number, since it is smaller than the sum of its proper divisors (16477463040).

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

9867721728 is a wasteful number, since it uses less digits than its factorization.

9867721728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5409 (or 5391 counting only the distinct ones).

The product of its digits is 4741632, while the sum is 57.

The square root of 9867721728 is about 99336.4068607276. The cubic root of 9867721728 is about 2144.8929969824.

The spelling of 9867721728 in words is "nine billion, eight hundred sixty-seven million, seven hundred twenty-one thousand, seven hundred twenty-eight".