128906681 has 4 divisors (see below), whose sum is σ = 131091600. Its totient is φ = 126721764.

The previous prime is 128906669. The next prime is 128906689. The reversal of 128906681 is 186609821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 128906681 - 2²² = 124712377 is a prime.

It is a super-2 number, since 2×128906681² = 33233864812871522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128906689) 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, 1092371 + ... + 1092488.

It is an arithmetic number, because the mean of its divisors is an integer number (32772900).

Almost surely, 2^128906681 is an apocalyptic number.

It is an amenable number.

128906681 is a deficient number, since it is larger than the sum of its proper divisors (2184919).

128906681 is an equidigital number, since it uses as much as digits as its factorization.

128906681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2184918.

The product of its (nonzero) digits is 41472, while the sum is 41.

The square root of 128906681 is about 11353.7078084650. The cubic root of 128906681 is about 505.1555655749.

The spelling of 128906681 in words is "one hundred twenty-eight million, nine hundred six thousand, six hundred eighty-one".