11521 has 4 divisors (see below), whose sum is σ = 11844. Its totient is φ = 11200.

The previous prime is 11519. The next prime is 11527. The reversal of 11521 is 12511.

It is a happy number.

11521 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3600 + 7921 = 60^2 + 89^2 .

It is a cyclic number.

It is not a de Polignac number, because 11521 - 2^{1} = 11519 is a prime.

It is a Duffinian number.

11521 is a lucky number.

It is a junction number, because it is equal to *n*+sod(*n*) for *n* = 11498 and 11507.

It is not an unprimeable number, because it can be changed into a prime (11527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 100 + ... + 181.

It is an arithmetic number, because the mean of its divisors is an integer number (2961).

It is a Proth number, since it is equal to 45 ⋅ 2^{8} + 1 and 45 < 2^{8}.

2^{11521} is an apocalyptic number.

It is an amenable number.

11521 is a deficient number, since it is larger than the sum of its proper divisors (323).

11521 is an equidigital number, since it uses as much as digits as its factorization.

11521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322.

The product of its digits is 10, while the sum is 10.

The square root of 11521 is about 107.3359212939. The cubic root of 11521 is about 22.5855181715.

Subtracting from 11521 its sum of digits (10), we obtain a palindrome (11511).

Subtracting 11521 from its reverse (12511), we obtain a triangular number (990 = T_{44}).

It can be divided in two parts, 115 and 21, that multiplied together give a triangular number (2415 = T_{69}).

The spelling of 11521 in words is "eleven thousand, five hundred twenty-one".

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