91028 has 12 divisors (see below), whose sum is σ = 182112. Its totient is φ = 39000.

The previous prime is 91019. The next prime is 91033. The reversal of 91028 is 82019.

91028 is an admirable number.

It is a hoax number, since the sum of its digits (20) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 91028.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1598 + ... + 1653.

It is an arithmetic number, because the mean of its divisors is an integer number (15176).

2⁹¹⁰²⁸ is an apocalyptic number.

It is an amenable number.

91028 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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 (91056).

91028 is a wasteful number, since it uses less digits than its factorization.

91028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3262 (or 3260 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 91028 is about 301.7084685586. The cubic root of 91028 is about 44.9840272530.

Subtracting from 91028 its reverse (82019), we obtain a palindrome (9009).

The spelling of 91028 in words is "ninety-one thousand, twenty-eight".