129128109 has 8 divisors (see below), whose sum is σ = 187822752. Its totient is φ = 78259440.

The previous prime is 129128063. The next prime is 129128119. The reversal of 129128109 is 901821921.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 129128109 - 2⁸ = 129127853 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 3912973 = 129128109 / (1 + 2 + 9 + 1 + 2 + 8 + 1 + 0 + 9).

It is a self number, because there is not a number n which added to its sum of digits gives 129128109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129128119) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1956454 + ... + 1956519.

It is an arithmetic number, because the mean of its divisors is an integer number (23477844).

Almost surely, 2^129128109 is an apocalyptic number.

It is an amenable number.

129128109 is a deficient number, since it is larger than the sum of its proper divisors (58694643).

129128109 is a wasteful number, since it uses less digits than its factorization.

129128109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3912987.

The product of its (nonzero) digits is 2592, while the sum is 33.

The square root of 129128109 is about 11363.4549763705. The cubic root of 129128109 is about 505.4446418807. Note that the first 3 decimals are identical.

The spelling of 129128109 in words is "one hundred twenty-nine million, one hundred twenty-eight thousand, one hundred nine".