128918091 has 4 divisors (see below), whose sum is σ = 171890792. Its totient is φ = 85945392.

The previous prime is 128918077. The next prime is 128918093. The reversal of 128918091 is 190819821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 190819821 = 3 ⋅63606607.

It is not a de Polignac number, because 128918091 - 2¹¹ = 128916043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128918093) 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, 21486346 + ... + 21486351.

It is an arithmetic number, because the mean of its divisors is an integer number (42972698).

Almost surely, 2^128918091 is an apocalyptic number.

128918091 is a deficient number, since it is larger than the sum of its proper divisors (42972701).

128918091 is an equidigital number, since it uses as much as digits as its factorization.

128918091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42972700.

The product of its (nonzero) digits is 10368, while the sum is 39.

The square root of 128918091 is about 11354.2102763689. The cubic root of 128918091 is about 505.1704695218.

The spelling of 128918091 in words is "one hundred twenty-eight million, nine hundred eighteen thousand, ninety-one".