21041 has 4 divisors (see below), whose sum is σ = 21492. Its totient is φ = 20592.

The previous prime is 21031. The next prime is 21059. The reversal of 21041 is 14012.

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 14641 + 6400 = 121^2 + 80^2 .

It is a cyclic number.

It is not a de Polignac number, because 21041 - 2¹⁴ = 4657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 146 + ... + 251.

It is an arithmetic number, because the mean of its divisors is an integer number (5373).

2²¹⁰⁴¹ is an apocalyptic number.

It is an amenable number.

21041 is a deficient number, since it is larger than the sum of its proper divisors (451).

21041 is an equidigital number, since it uses as much as digits as its factorization.

21041 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 450.

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 21041 is about 145.0551619212. The cubic root of 21041 is about 27.6071849949.

Adding to 21041 its reverse (14012), we get a palindrome (35053).

The spelling of 21041 in words is "twenty-one thousand, forty-one", and thus it is an iban number.