129556729 has 4 divisors (see below), whose sum is σ = 129583476. Its totient is φ = 129529984.

The previous prime is 129556709. The next prime is 129556829. The reversal of 129556729 is 927655921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 927655921 = 5477 ⋅169373.

It can be written as a sum of positive squares in 2 ways, for example, as 64722025 + 64834704 = 8045^2 + 8052^2 .

It is a cyclic number.

It is not a de Polignac number, because 129556729 - 2⁵ = 129556697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129556709) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3844 + ... + 16549.

It is an arithmetic number, because the mean of its divisors is an integer number (32395869).

Almost surely, 2^129556729 is an apocalyptic number.

It is an amenable number.

129556729 is a deficient number, since it is larger than the sum of its proper divisors (26747).

129556729 is an equidigital number, since it uses as much as digits as its factorization.

129556729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26746.

The product of its digits is 340200, while the sum is 46.

The square root of 129556729 is about 11382.2989329924. The cubic root of 129556729 is about 506.0032716542.

The spelling of 129556729 in words is "one hundred twenty-nine million, five hundred fifty-six thousand, seven hundred twenty-nine".