128799891 has 24 divisors (see below), whose sum is σ = 206406720. Its totient is φ = 76734000.

The previous prime is 128799889. The next prime is 128799907. The reversal of 128799891 is 198997821.

It is not a de Polignac number, because 128799891 - 2¹ = 128799889 is a prime.

It is a super-2 number, since 2×128799891² = 33178823843223762, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (128799851) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5185 + ... + 16866.

It is an arithmetic number, because the mean of its divisors is an integer number (8600280).

Almost surely, 2^128799891 is an apocalyptic number.

128799891 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

128799891 is a deficient number, since it is larger than the sum of its proper divisors (77606829).

128799891 is a wasteful number, since it uses less digits than its factorization.

128799891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22127 (or 22124 counting only the distinct ones).

The product of its digits is 653184, while the sum is 54.

The square root of 128799891 is about 11349.0039651064. The cubic root of 128799891 is about 505.0160319062.

The spelling of 128799891 in words is "one hundred twenty-eight million, seven hundred ninety-nine thousand, eight hundred ninety-one".