91440 has 60 divisors (see below), whose sum is σ = 309504. Its totient is φ = 24192.

The previous prime is 91433. The next prime is 91453. The reversal of 91440 is 4419.

It is a tau number, because it is divible by the number of its divisors (60).

It is a super-2 number, since 2×91440² = 16722547200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 91440.

It is an unprimeable number.

91440 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 11 ways as a sum of consecutive naturals, for example, 657 + ... + 783.

2⁹¹⁴⁴⁰ is an apocalyptic number.

91440 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (154752).

91440 is an abundant number, since it is smaller than the sum of its proper divisors (218064).

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

91440 is a wasteful number, since it uses less digits than its factorization.

91440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 91440 is about 302.3904760405. The cubic root of 91440 is about 45.0517922193.

Adding to 91440 its reverse (4419), we get a palindrome (95859).

The spelling of 91440 in words is "ninety-one thousand, four hundred forty".