128392921 has 8 divisors (see below), whose sum is σ = 130443264. Its totient is φ = 126349440.

The previous prime is 128392907. The next prime is 128392931. The reversal of 128392921 is 129293821.

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

It is a cyclic number.

It is not a de Polignac number, because 128392921 - 2⁹ = 128392409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128392931) 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 7 ways as a sum of consecutive naturals, for example, 46440 + ... + 49126.

It is an arithmetic number, because the mean of its divisors is an integer number (16305408).

Almost surely, 2^128392921 is an apocalyptic number.

It is an amenable number.

128392921 is a deficient number, since it is larger than the sum of its proper divisors (2050343).

128392921 is an equidigital number, since it uses as much as digits as its factorization.

128392921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3431.

The product of its digits is 15552, while the sum is 37.

The square root of 128392921 is about 11331.0600121966. The cubic root of 128392921 is about 504.4835696982.

The spelling of 128392921 in words is "one hundred twenty-eight million, three hundred ninety-two thousand, nine hundred twenty-one".