21421024421 has 2 divisors, whose sum is σ = 21421024422. Its totient is φ = 21421024420.

The previous prime is 21421024367. The next prime is 21421024423. The reversal of 21421024421 is 12442012412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12601185025 + 8819839396 = 112255^2 + 93914^2 .

It is a cyclic number.

It is not a de Polignac number, because 21421024421 - 2⁶ = 21421024357 is a prime.

Together with 21421024423, 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 (21421024423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710512210 + 10710512211.

It is an arithmetic number, because the mean of its divisors is an integer number (10710512211).

Almost surely, 2^21421024421 is an apocalyptic number.

It is an amenable number.

21421024421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21421024421 is an equidigital number, since it uses as much as digits as its factorization.

21421024421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21421024421 its reverse (12442012412), we get a palindrome (33863036833).

The spelling of 21421024421 in words is "twenty-one billion, four hundred twenty-one million, twenty-four thousand, four hundred twenty-one".