129197021 has 2 divisors, whose sum is σ = 129197022. Its totient is φ = 129197020.

The previous prime is 129197011. The next prime is 129197023. The reversal of 129197021 is 120791921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 128572921 + 624100 = 11339^2 + 790^2 .

It is a cyclic number.

It is not a de Polignac number, because 129197021 - 2²⁶ = 62088157 is a prime.

Together with 129197023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129197023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64598510 + 64598511.

It is an arithmetic number, because the mean of its divisors is an integer number (64598511).

Almost surely, 2^129197021 is an apocalyptic number.

It is an amenable number.

129197021 is a deficient number, since it is larger than the sum of its proper divisors (1).

129197021 is an equidigital number, since it uses as much as digits as its factorization.

129197021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2268, while the sum is 32.

The square root of 129197021 is about 11366.4867483317. The cubic root of 129197021 is about 505.5345397016.

The spelling of 129197021 in words is "one hundred twenty-nine million, one hundred ninety-seven thousand, twenty-one".