1211261312549 has 2 divisors, whose sum is σ = 1211261312550. Its totient is φ = 1211261312548.

The previous prime is 1211261312533. The next prime is 1211261312579. The reversal of 1211261312549 is 9452131621121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 948640936324 + 262620376225 = 973982^2 + 512465^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211261312549 - 2⁴ = 1211261312533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211261312579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605630656274 + 605630656275.

It is an arithmetic number, because the mean of its divisors is an integer number (605630656275).

Almost surely, 2^{1211261312549} is an apocalyptic number.

It is an amenable number.

1211261312549 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211261312549 is an equidigital number, since it uses as much as digits as its factorization.

1211261312549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 38.

The spelling of 1211261312549 in words is "one trillion, two hundred eleven billion, two hundred sixty-one million, three hundred twelve thousand, five hundred forty-nine".