129561823 has 2 divisors, whose sum is σ = 129561824. Its totient is φ = 129561822.

The previous prime is 129561799. The next prime is 129561847. The reversal of 129561823 is 328165921.

It is a balanced prime because it is at equal distance from previous prime (129561799) and next prime (129561847).

It is a cyclic number.

It is not a de Polignac number, because 129561823 - 2²⁵ = 96007391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (129561863) 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, 64780911 + 64780912.

It is an arithmetic number, because the mean of its divisors is an integer number (64780912).

Almost surely, 2^129561823 is an apocalyptic number.

129561823 is a deficient number, since it is larger than the sum of its proper divisors (1).

129561823 is an equidigital number, since it uses as much as digits as its factorization.

129561823 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 37.

The square root of 129561823 is about 11382.5226992965. The cubic root of 129561823 is about 506.0099033614.

The spelling of 129561823 in words is "one hundred twenty-nine million, five hundred sixty-one thousand, eight hundred twenty-three".