128197729 has 4 divisors (see below), whose sum is σ = 139852080. Its totient is φ = 116543380.

The previous prime is 128197721. The next prime is 128197739. The reversal of 128197729 is 927791821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 128197729 - 2³ = 128197721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128197721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5827159 + ... + 5827180.

It is an arithmetic number, because the mean of its divisors is an integer number (34963020).

Almost surely, 2^128197729 is an apocalyptic number.

It is an amenable number.

128197729 is a deficient number, since it is larger than the sum of its proper divisors (11654351).

128197729 is a wasteful number, since it uses less digits than its factorization.

128197729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11654350.

The product of its digits is 127008, while the sum is 46.

The square root of 128197729 is about 11322.4435966800. The cubic root of 128197729 is about 504.2277895007.

The spelling of 128197729 in words is "one hundred twenty-eight million, one hundred ninety-seven thousand, seven hundred twenty-nine".