128389181 has 4 divisors (see below), whose sum is σ = 128846364. Its totient is φ = 127932000.

The previous prime is 128389171. The next prime is 128389187. The reversal of 128389181 is 181983821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 181983821 = 53 ⋅3433657.

It can be written as a sum of positive squares in 2 ways, for example, as 76405081 + 51984100 = 8741^2 + 7210^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128389181 is a prime.

It is a super-2 number, since 2×128389181² = 32967563595701522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128389187) 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, 228170 + ... + 228731.

It is an arithmetic number, because the mean of its divisors is an integer number (32211591).

Almost surely, 2^128389181 is an apocalyptic number.

It is an amenable number.

128389181 is a deficient number, since it is larger than the sum of its proper divisors (457183).

128389181 is an equidigital number, since it uses as much as digits as its factorization.

128389181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 457182.

The product of its digits is 27648, while the sum is 41.

The square root of 128389181 is about 11330.8949778912. The cubic root of 128389181 is about 504.4786712275.

The spelling of 128389181 in words is "one hundred twenty-eight million, three hundred eighty-nine thousand, one hundred eighty-one".