129127543466221 has 2 divisors, whose sum is σ = 129127543466222. Its totient is φ = 129127543466220.

The previous prime is 129127543466209. The next prime is 129127543466231. The reversal of 129127543466221 is 122664345721921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70312602038121 + 58814941428100 = 8385261^2 + 7669090^2 .

It is a cyclic number.

It is not a de Polignac number, because 129127543466221 - 2⁷ = 129127543466093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129127543466231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64563771733110 + 64563771733111.

It is an arithmetic number, because the mean of its divisors is an integer number (64563771733111).

Almost surely, 2^{129127543466221} is an apocalyptic number.

It is an amenable number.

129127543466221 is a deficient number, since it is larger than the sum of its proper divisors (1).

129127543466221 is an equidigital number, since it uses as much as digits as its factorization.

129127543466221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8709120, while the sum is 55.

The spelling of 129127543466221 in words is "one hundred twenty-nine trillion, one hundred twenty-seven billion, five hundred forty-three million, four hundred sixty-six thousand, two hundred twenty-one".