91638 has 16 divisors (see below), whose sum is σ = 203760. Its totient is φ = 30528.

The previous prime is 91631. The next prime is 91639. The reversal of 91638 is 83619.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a plaindrome in base 14.

It is a nialpdrome in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 795 + ... + 902.

It is an arithmetic number, because the mean of its divisors is an integer number (12735).

2⁹¹⁶³⁸ is an apocalyptic number.

91638 is an abundant number, since it is smaller than the sum of its proper divisors (112122).

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 (101880).

91638 is a wasteful number, since it uses less digits than its factorization.

91638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1708 (or 1702 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 91638 is about 302.7176902660. The cubic root of 91638 is about 45.0842864745.

It can be divided in two parts, 91 and 638, that added together give a 6-th power (729 = 3⁶).

The spelling of 91638 in words is "ninety-one thousand, six hundred thirty-eight".