9999000721 has 4 divisors (see below), whose sum is σ = 10587177252. Its totient is φ = 9410824192.

The previous prime is 9999000709. The next prime is 9999000761. The reversal of 9999000721 is 1270009999.

9999000721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3120786496 + 6878214225 = 55864^2 + 82935^2 .

It is a cyclic number.

It is not a de Polignac number, because 9999000721 - 2⁵ = 9999000689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9999000701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 294088240 + ... + 294088273.

It is an arithmetic number, because the mean of its divisors is an integer number (2646794313).

Almost surely, 2^9999000721 is an apocalyptic number.

It is an amenable number.

9999000721 is a deficient number, since it is larger than the sum of its proper divisors (588176531).

9999000721 is a wasteful number, since it uses less digits than its factorization.

9999000721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 588176530.

The product of its (nonzero) digits is 91854, while the sum is 46.

The square root of 9999000721 is about 99995.0034801739. The cubic root of 9999000721 is about 2154.3629249300.

The spelling of 9999000721 in words is "nine billion, nine hundred ninety-nine million, seven hundred twenty-one", and thus it is an aban number.