23121890021 has 2 divisors, whose sum is σ = 23121890022. Its totient is φ = 23121890020.

The previous prime is 23121889969. The next prime is 23121890023. The reversal of 23121890021 is 12009812132.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14813567521 + 8308322500 = 121711^2 + 91150^2 .

It is a cyclic number.

It is not a de Polignac number, because 23121890021 - 2⁶ = 23121889957 is a prime.

It is a Sophie Germain prime.

Together with 23121890023, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23121890023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11560945010 + 11560945011.

It is an arithmetic number, because the mean of its divisors is an integer number (11560945011).

Almost surely, 2^23121890021 is an apocalyptic number.

It is an amenable number.

23121890021 is a deficient number, since it is larger than the sum of its proper divisors (1).

23121890021 is an equidigital number, since it uses as much as digits as its factorization.

23121890021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 29.

The spelling of 23121890021 in words is "twenty-three billion, one hundred twenty-one million, eight hundred ninety thousand, twenty-one".