91128 has 16 divisors (see below), whose sum is σ = 227880. Its totient is φ = 30368.

The previous prime is 91127. The next prime is 91129. The reversal of 91128 is 82119.

It is an interprime number because it is at equal distance from previous prime (91127) and next prime (91129).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91121) 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, 1875 + ... + 1922.

2⁹¹¹²⁸ is an apocalyptic number.

It is an amenable number.

91128 is an abundant number, since it is smaller than the sum of its proper divisors (136752).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113940).

91128 is a wasteful number, since it uses less digits than its factorization.

91128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3806 (or 3802 counting only the distinct ones).

The product of its digits is 144, while the sum is 21.

The square root of 91128 is about 301.8741459615. The cubic root of 91128 is about 45.0004938217. Note that the first 3 decimals are identical.

Subtracting from 91128 its reverse (82119), we obtain a palindrome (9009).

It can be divided in two parts, 911 and 28, that added together give a palindrome (939).

The spelling of 91128 in words is "ninety-one thousand, one hundred twenty-eight".