21513555439 has 2 divisors, whose sum is σ = 21513555440. Its totient is φ = 21513555438.

The previous prime is 21513555397. The next prime is 21513555463. The reversal of 21513555439 is 93455531512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21513555439 - 2⁷ = 21513555311 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21513555395 and 21513555404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21513556439) 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, 10756777719 + 10756777720.

It is an arithmetic number, because the mean of its divisors is an integer number (10756777720).

Almost surely, 2^21513555439 is an apocalyptic number.

21513555439 is a deficient number, since it is larger than the sum of its proper divisors (1).

21513555439 is an equidigital number, since it uses as much as digits as its factorization.

21513555439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 405000, while the sum is 43.

The spelling of 21513555439 in words is "twenty-one billion, five hundred thirteen million, five hundred fifty-five thousand, four hundred thirty-nine".