9728921 has 2 divisors, whose sum is σ = 9728922. Its totient is φ = 9728920.

The previous prime is 9728909. The next prime is 9728933. The reversal of 9728921 is 1298279.

9728921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (9728909) and next prime (9728933).

It can be written as a sum of positive squares in only one way, i.e., 9030025 + 698896 = 3005^2 + 836^2 .

It is an emirp because it is prime and its reverse (1298279) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9728921 is a prime.

It is not a weakly prime, because it can be changed into another prime (9728941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4864460 + 4864461.

It is an arithmetic number, because the mean of its divisors is an integer number (4864461).

Almost surely, 2^9728921 is an apocalyptic number.

It is an amenable number.

9728921 is a deficient number, since it is larger than the sum of its proper divisors (1).

9728921 is an equidigital number, since it uses as much as digits as its factorization.

9728921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 38.

The square root of 9728921 is about 3119.1218315417. The cubic root of 9728921 is about 213.4788685216.

The spelling of 9728921 in words is "nine million, seven hundred twenty-eight thousand, nine hundred twenty-one".