21343204121 has 2 divisors, whose sum is σ = 21343204122. Its totient is φ = 21343204120.

The previous prime is 21343204117. The next prime is 21343204123. The reversal of 21343204121 is 12140234312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11069354521 + 10273849600 = 105211^2 + 101360^2 .

It is a cyclic number.

It is not a de Polignac number, because 21343204121 - 2² = 21343204117 is a prime.

Together with 21343204123, 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 (21343204123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10671602060 + 10671602061.

It is an arithmetic number, because the mean of its divisors is an integer number (10671602061).

Almost surely, 2^21343204121 is an apocalyptic number.

It is an amenable number.

21343204121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21343204121 is an equidigital number, since it uses as much as digits as its factorization.

21343204121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 21343204121 its reverse (12140234312), we get a palindrome (33483438433).

The spelling of 21343204121 in words is "twenty-one billion, three hundred forty-three million, two hundred four thousand, one hundred twenty-one".