129475866521 has 2 divisors, whose sum is σ = 129475866522. Its totient is φ = 129475866520.

The previous prime is 129475866493. The next prime is 129475866571. The reversal of 129475866521 is 125668574921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120416634121 + 9059232400 = 347011^2 + 95180^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-129475866521 is a prime.

It is a super-2 number, since 2×129475866521² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (129475866571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64737933260 + 64737933261.

It is an arithmetic number, because the mean of its divisors is an integer number (64737933261).

Almost surely, 2^129475866521 is an apocalyptic number.

It is an amenable number.

129475866521 is a deficient number, since it is larger than the sum of its proper divisors (1).

129475866521 is an equidigital number, since it uses as much as digits as its factorization.

129475866521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7257600, while the sum is 56.

The spelling of 129475866521 in words is "one hundred twenty-nine billion, four hundred seventy-five million, eight hundred sixty-six thousand, five hundred twenty-one".