128397691 has 8 divisors (see below), whose sum is σ = 135773568. Its totient is φ = 121224000.

The previous prime is 128397683. The next prime is 128397697. The reversal of 128397691 is 196793821.

It is a happy number.

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 128397691 - 2³ = 128397683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128397697) 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, 49240 + ... + 51781.

It is an arithmetic number, because the mean of its divisors is an integer number (16971696).

Almost surely, 2^128397691 is an apocalyptic number.

128397691 is a deficient number, since it is larger than the sum of its proper divisors (7375877).

128397691 is a wasteful number, since it uses less digits than its factorization.

128397691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101093.

The product of its digits is 163296, while the sum is 46.

The square root of 128397691 is about 11331.2704936384. The cubic root of 128397691 is about 504.4898170749.

The spelling of 128397691 in words is "one hundred twenty-eight million, three hundred ninety-seven thousand, six hundred ninety-one".