9913721 has 2 divisors, whose sum is σ = 9913722. Its totient is φ = 9913720.

The previous prime is 9913697. The next prime is 9913723. The reversal of 9913721 is 1273199.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9388096 + 525625 = 3064^2 + 725^2 .

It is an emirp because it is prime and its reverse (1273199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9913721 is a prime.

It is a Sophie Germain prime.

Together with 9913723, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (9913723) 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 as a sum of consecutive naturals, namely, 4956860 + 4956861.

It is an arithmetic number, because the mean of its divisors is an integer number (4956861).

Almost surely, 2^9913721 is an apocalyptic number.

It is an amenable number.

9913721 is a deficient number, since it is larger than the sum of its proper divisors (1).

9913721 is an equidigital number, since it uses as much as digits as its factorization.

9913721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3402, while the sum is 32.

The square root of 9913721 is about 3148.6061995747. The cubic root of 9913721 is about 214.8220702042.

The spelling of 9913721 in words is "nine million, nine hundred thirteen thousand, seven hundred twenty-one".