91805 has 16 divisors (see below), whose sum is σ = 130944. Its totient is φ = 60480.

The previous prime is 91801. The next prime is 91807. The reversal of 91805 is 50819.

91805 = T₄₄ + T₄₅ + ... + T₈₅.

It is not a de Polignac number, because 91805 - 2² = 91801 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 16.

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 91805.

It is not an unprimeable number, because it can be changed into a prime (91801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1475 + ... + 1535.

It is an arithmetic number, because the mean of its divisors is an integer number (8184).

2⁹¹⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

91805 is a deficient number, since it is larger than the sum of its proper divisors (39139).

91805 is a wasteful number, since it uses less digits than its factorization.

91805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 91805 is about 302.9933992680. The cubic root of 91805 is about 45.1116568771. Note that the first 3 decimals are identical.

The spelling of 91805 in words is "ninety-one thousand, eight hundred five".