12543721639 has 2 divisors, whose sum is σ = 12543721640. Its totient is φ = 12543721638.

The previous prime is 12543721637. The next prime is 12543721667. The reversal of 12543721639 is 93612734521.

It is a weak prime.

It is an emirp because it is prime and its reverse (93612734521) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12543721639 - 2¹ = 12543721637 is a prime.

Together with 12543721637, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 12543721595 and 12543721604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12543721637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6271860819 + 6271860820.

It is an arithmetic number, because the mean of its divisors is an integer number (6271860820).

Almost surely, 2^12543721639 is an apocalyptic number.

12543721639 is a deficient number, since it is larger than the sum of its proper divisors (1).

12543721639 is an equidigital number, since it uses as much as digits as its factorization.

12543721639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 272160, while the sum is 43.

The spelling of 12543721639 in words is "twelve billion, five hundred forty-three million, seven hundred twenty-one thousand, six hundred thirty-nine".