128812729 has 4 divisors (see below), whose sum is σ = 129375460. Its totient is φ = 128250000.

The previous prime is 128812721. The next prime is 128812741. The reversal of 128812729 is 927218821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 126517504 + 2295225 = 11248^2 + 1515^2 .

It is a cyclic number.

It is not a de Polignac number, because 128812729 - 2³ = 128812721 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 128812691 and 128812700.

It is not an unprimeable number, because it can be changed into a prime (128812721) 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, 281022 + ... + 281479.

It is an arithmetic number, because the mean of its divisors is an integer number (32343865).

Almost surely, 2^128812729 is an apocalyptic number.

It is an amenable number.

128812729 is a deficient number, since it is larger than the sum of its proper divisors (562731).

128812729 is an equidigital number, since it uses as much as digits as its factorization.

128812729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562730.

The product of its digits is 32256, while the sum is 40.

The square root of 128812729 is about 11349.5695513090. The cubic root of 128812729 is about 505.0328103376.

The spelling of 128812729 in words is "one hundred twenty-eight million, eight hundred twelve thousand, seven hundred twenty-nine".