9939721 has 8 divisors (see below), whose sum is σ = 11217600. Its totient is φ = 8724240.

The previous prime is 9939707. The next prime is 9939731. The reversal of 9939721 is 1279399.

9939721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 9939721 - 2²³ = 1551113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9939731) 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, 15261 + ... + 15898.

It is an arithmetic number, because the mean of its divisors is an integer number (1402200).

Almost surely, 2^9939721 is an apocalyptic number.

It is an amenable number.

9939721 is a deficient number, since it is larger than the sum of its proper divisors (1277879).

9939721 is a wasteful number, since it uses less digits than its factorization.

9939721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31199.

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

The square root of 9939721 is about 3152.7323070632. The cubic root of 9939721 is about 215.0097057093.

The spelling of 9939721 in words is "nine million, nine hundred thirty-nine thousand, seven hundred twenty-one".