12947778549581 has 2 divisors, whose sum is σ = 12947778549582. Its totient is φ = 12947778549580.

The previous prime is 12947778549533. The next prime is 12947778549619. The reversal of 12947778549581 is 18594587774921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12944380708900 + 3397840681 = 3597830^2 + 58291^2 .

It is an emirp because it is prime and its reverse (18594587774921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12947778549581 - 2²⁶ = 12947711440717 is a prime.

It is a super-2 number, since 2×12947778549581² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12947778549481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6473889274790 + 6473889274791.

It is an arithmetic number, because the mean of its divisors is an integer number (6473889274791).

Almost surely, 2^{12947778549581} is an apocalyptic number.

It is an amenable number.

12947778549581 is a deficient number, since it is larger than the sum of its proper divisors (1).

12947778549581 is an equidigital number, since it uses as much as digits as its factorization.

12947778549581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1422489600, while the sum is 77.

The spelling of 12947778549581 in words is "twelve trillion, nine hundred forty-seven billion, seven hundred seventy-eight million, five hundred forty-nine thousand, five hundred eighty-one".