129170021 has 2 divisors, whose sum is σ = 129170022. Its totient is φ = 129170020.

The previous prime is 129170003. The next prime is 129170033. The reversal of 129170021 is 120071921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66601921 + 62568100 = 8161^2 + 7910^2 .

It is a cyclic number.

It is not a de Polignac number, because 129170021 - 2¹⁰ = 129168997 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129170051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64585010 + 64585011.

It is an arithmetic number, because the mean of its divisors is an integer number (64585011).

Almost surely, 2^129170021 is an apocalyptic number.

It is an amenable number.

129170021 is a deficient number, since it is larger than the sum of its proper divisors (1).

129170021 is an equidigital number, since it uses as much as digits as its factorization.

129170021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 23.

The square root of 129170021 is about 11365.2989841887. The cubic root of 129170021 is about 505.4993211819.

The spelling of 129170021 in words is "one hundred twenty-nine million, one hundred seventy thousand, twenty-one".