21444001421 has 2 divisors, whose sum is σ = 21444001422. Its totient is φ = 21444001420.

The previous prime is 21444001393. The next prime is 21444001471. The reversal of 21444001421 is 12410044412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11042857225 + 10401144196 = 105085^2 + 101986^2 .

It is a cyclic number.

It is not a de Polignac number, because 21444001421 - 2⁶ = 21444001357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21444001471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722000710 + 10722000711.

It is an arithmetic number, because the mean of its divisors is an integer number (10722000711).

Almost surely, 2^21444001421 is an apocalyptic number.

It is an amenable number.

21444001421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21444001421 is an equidigital number, since it uses as much as digits as its factorization.

21444001421 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 21444001421 its reverse (12410044412), we get a palindrome (33854045833).

The spelling of 21444001421 in words is "twenty-one billion, four hundred forty-four million, one thousand, four hundred twenty-one".