9993721 has 4 divisors (see below), whose sum is σ = 10106100. Its totient is φ = 9881344.

The previous prime is 9993713. The next prime is 9993743. The reversal of 9993721 is 1273999.

9993721 is digitally balanced in base 3, 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 6969600 + 3024121 = 2640^2 + 1739^2 .

It is a cyclic number.

It is not a de Polignac number, because 9993721 - 2³ = 9993713 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9993701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56056 + ... + 56233.

It is an arithmetic number, because the mean of its divisors is an integer number (2526525).

Almost surely, 2^9993721 is an apocalyptic number.

It is an amenable number.

9993721 is a deficient number, since it is larger than the sum of its proper divisors (112379).

9993721 is a wasteful number, since it uses less digits than its factorization.

9993721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112378.

The product of its digits is 30618, while the sum is 40.

The square root of 9993721 is about 3161.2847072037. The cubic root of 9993721 is about 215.3983672440.

The spelling of 9993721 in words is "nine million, nine hundred ninety-three thousand, seven hundred twenty-one".