128856391891 has 8 divisors (see below), whose sum is σ = 129004368768. Its totient is φ = 128708496000.

The previous prime is 128856391861. The next prime is 128856391901. The reversal of 128856391891 is 198193658821.

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 128856391891 - 2¹¹ = 128856389843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128856391861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3508081 + ... + 3544621.

It is an arithmetic number, because the mean of its divisors is an integer number (16125546096).

Almost surely, 2^128856391891 is an apocalyptic number.

128856391891 is a deficient number, since it is larger than the sum of its proper divisors (147976877).

128856391891 is a wasteful number, since it uses less digits than its factorization.

128856391891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40493.

The product of its digits is 7464960, while the sum is 61.

The spelling of 128856391891 in words is "one hundred twenty-eight billion, eight hundred fifty-six million, three hundred ninety-one thousand, eight hundred ninety-one".