128555111 has 4 divisors (see below), whose sum is σ = 130473912. Its totient is φ = 126636312.

The previous prime is 128555101. The next prime is 128555129. The reversal of 128555111 is 111555821.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128555111 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128555101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 959300 + ... + 959433.

It is an arithmetic number, because the mean of its divisors is an integer number (32618478).

Almost surely, 2^128555111 is an apocalyptic number.

128555111 is a deficient number, since it is larger than the sum of its proper divisors (1918801).

128555111 is an equidigital number, since it uses as much as digits as its factorization.

128555111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1918800.

The product of its digits is 2000, while the sum is 29.

The square root of 128555111 is about 11338.2146301788. The cubic root of 128555111 is about 504.6959068484.

The spelling of 128555111 in words is "one hundred twenty-eight million, five hundred fifty-five thousand, one hundred eleven".