12815138549 has 2 divisors, whose sum is σ = 12815138550. Its totient is φ = 12815138548.

The previous prime is 12815138537. The next prime is 12815138573. The reversal of 12815138549 is 94583151821.

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., 12452997649 + 362140900 = 111593^2 + 19030^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12815138549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12815135549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6407569274 + 6407569275.

It is an arithmetic number, because the mean of its divisors is an integer number (6407569275).

Almost surely, 2^12815138549 is an apocalyptic number.

It is an amenable number.

12815138549 is a deficient number, since it is larger than the sum of its proper divisors (1).

12815138549 is an equidigital number, since it uses as much as digits as its factorization.

12815138549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345600, while the sum is 47.

The spelling of 12815138549 in words is "twelve billion, eight hundred fifteen million, one hundred thirty-eight thousand, five hundred forty-nine".