21115503245549 has 2 divisors, whose sum is σ = 21115503245550. Its totient is φ = 21115503245548.

The previous prime is 21115503245491. The next prime is 21115503245591. The reversal of 21115503245549 is 94554230551112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14707086940324 + 6408416305225 = 3834982^2 + 2531485^2 .

It is a cyclic number.

It is not a de Polignac number, because 21115503245549 - 2²⁰ = 21115502196973 is a prime.

It is a super-2 number, since 2×21115503245549² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21115503215549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557751622774 + 10557751622775.

It is an arithmetic number, because the mean of its divisors is an integer number (10557751622775).

Almost surely, 2^{21115503245549} is an apocalyptic number.

It is an amenable number.

21115503245549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115503245549 is an equidigital number, since it uses as much as digits as its factorization.

21115503245549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080000, while the sum is 47.

The spelling of 21115503245549 in words is "twenty-one trillion, one hundred fifteen billion, five hundred three million, two hundred forty-five thousand, five hundred forty-nine".