129505823 has 2 divisors, whose sum is σ = 129505824. Its totient is φ = 129505822.

The previous prime is 129505799. The next prime is 129505829. The reversal of 129505823 is 328505921.

It is a strong prime.

It is an emirp because it is prime and its reverse (328505921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 129505823 - 2⁸ = 129505567 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129505829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64752911 + 64752912.

It is an arithmetic number, because the mean of its divisors is an integer number (64752912).

Almost surely, 2^129505823 is an apocalyptic number.

129505823 is a deficient number, since it is larger than the sum of its proper divisors (1).

129505823 is an equidigital number, since it uses as much as digits as its factorization.

129505823 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21600, while the sum is 35.

The square root of 129505823 is about 11380.0625217966. The cubic root of 129505823 is about 505.9369892948.

The spelling of 129505823 in words is "one hundred twenty-nine million, five hundred five thousand, eight hundred twenty-three".