91645 has 4 divisors (see below), whose sum is σ = 109980. Its totient is φ = 73312.

The previous prime is 91639. The next prime is 91673. The reversal of 91645 is 54619.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54619 = 193 ⋅283.

It can be written as a sum of positive squares in 2 ways, for example, as 39204 + 52441 = 198^2 + 229^2 .

It is a cyclic number.

It is not a de Polignac number, because 91645 - 2¹¹ = 89597 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9160 + ... + 9169.

It is an arithmetic number, because the mean of its divisors is an integer number (27495).

2⁹¹⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

91645 is a deficient number, since it is larger than the sum of its proper divisors (18335).

91645 is a wasteful number, since it uses less digits than its factorization.

91645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18334.

The product of its digits is 1080, while the sum is 25.

The square root of 91645 is about 302.7292519728. The cubic root of 91645 is about 45.0854344043.

It can be divided in two parts, 916 and 45, that added together give a square (961 = 31²).

The spelling of 91645 in words is "ninety-one thousand, six hundred forty-five".