9908721 has 12 divisors (see below), whose sum is σ = 14583348. Its totient is φ = 6480864.

The previous prime is 9908719. The next prime is 9908729. The reversal of 9908721 is 1278099.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 8381025 + 1527696 = 2895^2 + 1236^2 .

It is not a de Polignac number, because 9908721 - 2¹ = 9908719 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9908729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9910 + ... + 10863.

It is an arithmetic number, because the mean of its divisors is an integer number (1215279).

Almost surely, 2^9908721 is an apocalyptic number.

It is an amenable number.

9908721 is a deficient number, since it is larger than the sum of its proper divisors (4674627).

9908721 is a wasteful number, since it uses less digits than its factorization.

9908721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20832 (or 20829 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 9908721 is about 3147.8120973146. The cubic root of 9908721 is about 214.7859488536.

The spelling of 9908721 in words is "nine million, nine hundred eight thousand, seven hundred twenty-one".