21420223421 has 2 divisors, whose sum is σ = 21420223422. Its totient is φ = 21420223420.

The previous prime is 21420223411. The next prime is 21420223459. The reversal of 21420223421 is 12432202412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20292002500 + 1128220921 = 142450^2 + 33589^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420223421 - 2¹⁴ = 21420207037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21420223411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710111710 + 10710111711.

It is an arithmetic number, because the mean of its divisors is an integer number (10710111711).

Almost surely, 2^21420223421 is an apocalyptic number.

It is an amenable number.

21420223421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420223421 is an equidigital number, since it uses as much as digits as its factorization.

21420223421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1536, while the sum is 23.

Adding to 21420223421 its reverse (12432202412), we get a palindrome (33852425833).

The spelling of 21420223421 in words is "twenty-one billion, four hundred twenty million, two hundred twenty-three thousand, four hundred twenty-one".