9967721 has 2 divisors, whose sum is σ = 9967722. Its totient is φ = 9967720.

The previous prime is 9967703. The next prime is 9967759. The reversal of 9967721 is 1277699.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9834496 + 133225 = 3136^2 + 365^2 .

It is an emirp because it is prime and its reverse (1277699) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9967721 is a prime.

It is not a weakly prime, because it can be changed into another prime (9967781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4983860 + 4983861.

It is an arithmetic number, because the mean of its divisors is an integer number (4983861).

Almost surely, 2^9967721 is an apocalyptic number.

It is an amenable number.

9967721 is a deficient number, since it is larger than the sum of its proper divisors (1).

9967721 is an equidigital number, since it uses as much as digits as its factorization.

9967721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 47628, while the sum is 41.

The square root of 9967721 is about 3157.1697768730. The cubic root of 9967721 is about 215.2114091439.

The spelling of 9967721 in words is "nine million, nine hundred sixty-seven thousand, seven hundred twenty-one".