21129038549 has 2 divisors, whose sum is σ = 21129038550. Its totient is φ = 21129038548.

The previous prime is 21129038537. The next prime is 21129038587. The reversal of 21129038549 is 94583092112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20052542449 + 1076496100 = 141607^2 + 32810^2 .

It is a cyclic number.

It is not a de Polignac number, because 21129038549 - 2⁴ = 21129038533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21129038509) 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, 10564519274 + 10564519275.

It is an arithmetic number, because the mean of its divisors is an integer number (10564519275).

Almost surely, 2^21129038549 is an apocalyptic number.

It is an amenable number.

21129038549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21129038549 is an equidigital number, since it uses as much as digits as its factorization.

21129038549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 44.

The spelling of 21129038549 in words is "twenty-one billion, one hundred twenty-nine million, thirty-eight thousand, five hundred forty-nine".