91840 has 56 divisors (see below), whose sum is σ = 256032. Its totient is φ = 30720.

The previous prime is 91837. The next prime is 91841. The reversal of 91840 is 4819.

91840 is nontrivially palindromic in base 3.

It is a tau number, because it is divible by the number of its divisors (56).

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (91841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2220 + ... + 2260.

It is an arithmetic number, because the mean of its divisors is an integer number (4572).

2⁹¹⁸⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128016).

91840 is an abundant number, since it is smaller than the sum of its proper divisors (164192).

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

91840 is a wasteful number, since it uses less digits than its factorization.

91840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65 (or 55 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 91840 is about 303.0511507980. The cubic root of 91840 is about 45.1173889809.

It can be divided in two parts, 9 and 1840, that added together give a square (1849 = 43²).

The spelling of 91840 in words is "ninety-one thousand, eight hundred forty".