91780 has 24 divisors (see below), whose sum is σ = 208152. Its totient is φ = 33792.

The previous prime is 91771. The next prime is 91781. The reversal of 91780 is 8719.

It can be written as a sum of positive squares in 4 ways, for example, as 576 + 91204 = 24^2 + 302^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91781) by changing a digit.

91780 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 7 ways as a sum of consecutive naturals, for example, 84 + ... + 436.

It is an arithmetic number, because the mean of its divisors is an integer number (8673).

2⁹¹⁷⁸⁰ 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 91780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104076).

91780 is an abundant number, since it is smaller than the sum of its proper divisors (116372).

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

91780 is a wasteful number, since it uses less digits than its factorization.

91780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375 (or 373 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 91780 is about 302.9521414349. The cubic root of 91780 is about 45.1075616251.

The spelling of 91780 in words is "ninety-one thousand, seven hundred eighty".