9721421 has 2 divisors, whose sum is σ = 9721422. Its totient is φ = 9721420.

The previous prime is 9721373. The next prime is 9721423. The reversal of 9721421 is 1241279.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9523396 + 198025 = 3086^2 + 445^2 .

It is a cyclic number.

It is not a de Polignac number, because 9721421 - 2⁶ = 9721357 is a prime.

Together with 9721423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9721423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4860710 + 4860711.

It is an arithmetic number, because the mean of its divisors is an integer number (4860711).

Almost surely, 2^9721421 is an apocalyptic number.

It is an amenable number.

9721421 is a deficient number, since it is larger than the sum of its proper divisors (1).

9721421 is an equidigital number, since it uses as much as digits as its factorization.

9721421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008, while the sum is 26.

The square root of 9721421 is about 3117.9193382767. The cubic root of 9721421 is about 213.4239976503.

The spelling of 9721421 in words is "nine million, seven hundred twenty-one thousand, four hundred twenty-one".