21144443081 has 2 divisors, whose sum is σ = 21144443082. Its totient is φ = 21144443080.

The previous prime is 21144443077. The next prime is 21144443123. The reversal of 21144443081 is 18034444112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11774203081 + 9370240000 = 108509^2 + 96800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21144443081 - 2² = 21144443077 is a prime.

It is a super-2 number, since 2×21144443081² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21144443011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572221540 + 10572221541.

It is an arithmetic number, because the mean of its divisors is an integer number (10572221541).

Almost surely, 2^21144443081 is an apocalyptic number.

It is an amenable number.

21144443081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144443081 is an equidigital number, since it uses as much as digits as its factorization.

21144443081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12288, while the sum is 32.

Adding to 21144443081 its reverse (18034444112), we get a palindrome (39178887193).

The spelling of 21144443081 in words is "twenty-one billion, one hundred forty-four million, four hundred forty-three thousand, eighty-one".