128928399 has 4 divisors (see below), whose sum is σ = 171904536. Its totient is φ = 85952264.

The previous prime is 128928377. The next prime is 128928407. The reversal of 128928399 is 993829821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 993829821 = 3 ⋅331276607.

It is a cyclic number.

It is not a de Polignac number, because 128928399 - 2¹⁵ = 128895631 is a prime.

It is a super-3 number, since 3×128928399³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128924399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21488064 + ... + 21488069.

It is an arithmetic number, because the mean of its divisors is an integer number (42976134).

Almost surely, 2^128928399 is an apocalyptic number.

128928399 is a deficient number, since it is larger than the sum of its proper divisors (42976137).

128928399 is an equidigital number, since it uses as much as digits as its factorization.

128928399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42976136.

The product of its digits is 559872, while the sum is 51.

The square root of 128928399 is about 11354.6641958272. The cubic root of 128928399 is about 505.1839332603.

The spelling of 128928399 in words is "one hundred twenty-eight million, nine hundred twenty-eight thousand, three hundred ninety-nine".