21323112521 has 2 divisors, whose sum is σ = 21323112522. Its totient is φ = 21323112520.

The previous prime is 21323112487. The next prime is 21323112523. The reversal of 21323112521 is 12521132312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16780352521 + 4542760000 = 129539^2 + 67400^2 .

It is a cyclic number.

It is not a de Polignac number, because 21323112521 - 2¹⁰ = 21323111497 is a prime.

Together with 21323112523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21323112523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10661556260 + 10661556261.

It is an arithmetic number, because the mean of its divisors is an integer number (10661556261).

Almost surely, 2^21323112521 is an apocalyptic number.

It is an amenable number.

21323112521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21323112521 is an equidigital number, since it uses as much as digits as its factorization.

21323112521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 720, while the sum is 23.

Adding to 21323112521 its reverse (12521132312), we get a palindrome (33844244833).

The spelling of 21323112521 in words is "twenty-one billion, three hundred twenty-three million, one hundred twelve thousand, five hundred twenty-one".