21148469981809 has 2 divisors, whose sum is σ = 21148469981810. Its totient is φ = 21148469981808.

The previous prime is 21148469981801. The next prime is 21148469981819. The reversal of 21148469981809 is 90818996484112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12394729978225 + 8753740003584 = 3520615^2 + 2958672^2 .

It is a cyclic number.

It is not a de Polignac number, because 21148469981809 - 2³ = 21148469981801 is a prime.

It is not a weakly prime, because it can be changed into another prime (21148469981801) 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, 10574234990904 + 10574234990905.

It is an arithmetic number, because the mean of its divisors is an integer number (10574234990905).

Almost surely, 2^{21148469981809} is an apocalyptic number.

It is an amenable number.

21148469981809 is a deficient number, since it is larger than the sum of its proper divisors (1).

21148469981809 is an equidigital number, since it uses as much as digits as its factorization.

21148469981809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 71663616, while the sum is 70.

The spelling of 21148469981809 in words is "twenty-one trillion, one hundred forty-eight billion, four hundred sixty-nine million, nine hundred eighty-one thousand, eight hundred nine".