9979597921 has 2 divisors, whose sum is σ = 9979597922. Its totient is φ = 9979597920.

The previous prime is 9979597919. The next prime is 9979597963. The reversal of 9979597921 is 1297959799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8320176225 + 1659421696 = 91215^2 + 40736^2 .

It is an emirp because it is prime and its reverse (1297959799) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9979597921 - 2¹ = 9979597919 is a prime.

Together with 9979597919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (9979597321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4989798960 + 4989798961.

It is an arithmetic number, because the mean of its divisors is an integer number (4989798961).

Almost surely, 2^9979597921 is an apocalyptic number.

It is an amenable number.

9979597921 is a deficient number, since it is larger than the sum of its proper divisors (1).

9979597921 is an equidigital number, since it uses as much as digits as its factorization.

9979597921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28934010, while the sum is 67.

The square root of 9979597921 is about 99897.9375212522. The cubic root of 9979597921 is about 2152.9685275958.

The spelling of 9979597921 in words is "nine billion, nine hundred seventy-nine million, five hundred ninety-seven thousand, nine hundred twenty-one".