21444004013 has 2 divisors, whose sum is σ = 21444004014. Its totient is φ = 21444004012.

The previous prime is 21444004009. The next prime is 21444004073. The reversal of 21444004013 is 31040044412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21128657449 + 315346564 = 145357^2 + 17758^2 .

It is a cyclic number.

It is not a de Polignac number, because 21444004013 - 2² = 21444004009 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21444004013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21444004073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722002006 + 10722002007.

It is an arithmetic number, because the mean of its divisors is an integer number (10722002007).

Almost surely, 2^21444004013 is an apocalyptic number.

It is an amenable number.

21444004013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21444004013 is an equidigital number, since it uses as much as digits as its factorization.

21444004013 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 21444004013 its reverse (31040044412), we get a palindrome (52484048425).

The spelling of 21444004013 in words is "twenty-one billion, four hundred forty-four million, four thousand, thirteen".