21479081549 has 2 divisors, whose sum is σ = 21479081550. Its totient is φ = 21479081548.

The previous prime is 21479081543. The next prime is 21479081621. The reversal of 21479081549 is 94518097412.

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., 19221881449 + 2257200100 = 138643^2 + 47510^2 .

It is a cyclic number.

It is not a de Polignac number, because 21479081549 - 2¹² = 21479077453 is a prime.

It is a super-2 number, since 2×21479081549² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21479081497 and 21479081506.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21479081543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10739540774 + 10739540775.

It is an arithmetic number, because the mean of its divisors is an integer number (10739540775).

Almost surely, 2^21479081549 is an apocalyptic number.

It is an amenable number.

21479081549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21479081549 is an equidigital number, since it uses as much as digits as its factorization.

21479081549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 725760, while the sum is 50.

The spelling of 21479081549 in words is "twenty-one billion, four hundred seventy-nine million, eighty-one thousand, five hundred forty-nine".