11565 has 12 divisors (see below), whose sum is σ = 20124. Its totient is φ = 6144.

The previous prime is 11551. The next prime is 11579. The reversal of 11565 is 56511.

11565 is nontrivially palindromic in base 2.

11565 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (11551) and next prime (11579).

It can be written as a sum of positive squares in 2 ways, for example, as 8649 + 2916 = 93^2 + 54^2 .

It is not a de Polignac number, because 11565 - 2⁴ = 11549 is a prime.

11565 is an undulating number in base 16.

It is a Curzon number.

It is a nialpdrome in base 11.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 84 + ... + 173.

It is an arithmetic number, because the mean of its divisors is an integer number (1677).

2¹¹⁵⁶⁵ is an apocalyptic number.

11565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

11565 is a deficient number, since it is larger than the sum of its proper divisors (8559).

11565 is a wasteful number, since it uses less digits than its factorization.

11565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268 (or 265 counting only the distinct ones).

The product of its digits is 150, while the sum is 18.

The square root of 11565 is about 107.5406899736. The cubic root of 11565 is about 22.6142338611.

It can be divided in two parts, 11 and 565, that added together give a square (576 = 24²).

The spelling of 11565 in words is "eleven thousand, five hundred sixty-five".