9721919 has 2 divisors, whose sum is σ = 9721920. Its totient is φ = 9721918.

The previous prime is 9721897. The next prime is 9721927. The reversal of 9721919 is 9191279.

9721919 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is an emirp because it is prime and its reverse (9191279) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9721919 is a prime.

It is a super-2 number, since 2×9721919² = 189031418085122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9721969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4860959 + 4860960.

It is an arithmetic number, because the mean of its divisors is an integer number (4860960).

Almost surely, 2^9721919 is an apocalyptic number.

9721919 is a deficient number, since it is larger than the sum of its proper divisors (1).

9721919 is an equidigital number, since it uses as much as digits as its factorization.

9721919 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10206, while the sum is 38.

The square root of 9721919 is about 3117.9991982039. Note that the first 3 decimals coincide. The cubic root of 9721919 is about 213.4276419507.

The spelling of 9721919 in words is "nine million, seven hundred twenty-one thousand, nine hundred nineteen".