128858172037891 has 4 divisors (see below), whose sum is σ = 130781428337032. Its totient is φ = 126934915738752.

The previous prime is 128858172037883. The next prime is 128858172037909. The reversal of 128858172037891 is 198730271858821.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 128858172037891 - 2³ = 128858172037883 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 128858172037891.

It is not an unprimeable number, because it can be changed into a prime (128858172037811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 961628149470 + ... + 961628149603.

It is an arithmetic number, because the mean of its divisors is an integer number (32695357084258).

Almost surely, 2^{128858172037891} is an apocalyptic number.

128858172037891 is a deficient number, since it is larger than the sum of its proper divisors (1923256299141).

128858172037891 is an equidigital number, since it uses as much as digits as its factorization.

128858172037891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1923256299140.

The product of its (nonzero) digits is 108380160, while the sum is 70.

The spelling of 128858172037891 in words is "one hundred twenty-eight trillion, eight hundred fifty-eight billion, one hundred seventy-two million, thirty-seven thousand, eight hundred ninety-one".