128396921 has 8 divisors (see below), whose sum is σ = 130757760. Its totient is φ = 126042352.

The previous prime is 128396911. The next prime is 128396923. The reversal of 128396921 is 129693821.

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 128396921 - 2¹⁴ = 128380537 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (128396923) 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, 64091 + ... + 66063.

It is an arithmetic number, because the mean of its divisors is an integer number (16344720).

It is a Poulet number, since it divides 2^128396920-1.

Almost surely, 2^128396921 is an apocalyptic number.

It is an amenable number.

128396921 is a deficient number, since it is larger than the sum of its proper divisors (2360839).

128396921 is a wasteful number, since it uses less digits than its factorization.

128396921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3135.

The product of its digits is 46656, while the sum is 41.

The square root of 128396921 is about 11331.2365168149. The cubic root of 128396921 is about 504.4888085990.

The spelling of 128396921 in words is "one hundred twenty-eight million, three hundred ninety-six thousand, nine hundred twenty-one".