21055666142729 has 2 divisors, whose sum is σ = 21055666142730. Its totient is φ = 21055666142728.

The previous prime is 21055666142653. The next prime is 21055666142741. The reversal of 21055666142729 is 92724166655012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21016017368329 + 39648774400 = 4584323^2 + 199120^2 .

It is a cyclic number.

It is not a de Polignac number, because 21055666142729 - 2²⁰ = 21055665094153 is a prime.

It is not a weakly prime, because it can be changed into another prime (21055666142789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527833071364 + 10527833071365.

It is an arithmetic number, because the mean of its divisors is an integer number (10527833071365).

Almost surely, 2^{21055666142729} is an apocalyptic number.

It is an amenable number.

21055666142729 is a deficient number, since it is larger than the sum of its proper divisors (1).

21055666142729 is an equidigital number, since it uses as much as digits as its factorization.

21055666142729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10886400, while the sum is 56.

The spelling of 21055666142729 in words is "twenty-one trillion, fifty-five billion, six hundred sixty-six million, one hundred forty-two thousand, seven hundred twenty-nine".