128972729 has 4 divisors (see below), whose sum is σ = 129008784. Its totient is φ = 128936676.

The previous prime is 128972717. The next prime is 128972737. The reversal of 128972729 is 927279821.

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 128972729 - 2¹² = 128968633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128972749) 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, 11987 + ... + 20040.

It is an arithmetic number, because the mean of its divisors is an integer number (32252196).

Almost surely, 2^128972729 is an apocalyptic number.

It is an amenable number.

128972729 is a deficient number, since it is larger than the sum of its proper divisors (36055).

128972729 is an equidigital number, since it uses as much as digits as its factorization.

128972729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36054.

The product of its digits is 254016, while the sum is 47.

The square root of 128972729 is about 11356.6160893111. The cubic root of 128972729 is about 505.2418264727.

The spelling of 128972729 in words is "one hundred twenty-eight million, nine hundred seventy-two thousand, seven hundred twenty-nine".