21441 has 8 divisors (see below), whose sum is σ = 32704. Its totient is φ = 12240.

The previous prime is 21433. The next prime is 21467. The reversal of 21441 is 14412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21441 - 2³ = 21433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 490 + ... + 531.

It is an arithmetic number, because the mean of its divisors is an integer number (4088).

2²¹⁴⁴¹ is an apocalyptic number.

21441 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21441 is a deficient number, since it is larger than the sum of its proper divisors (11263).

21441 is a wasteful number, since it uses less digits than its factorization.

21441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1031.

The product of its digits is 32, while the sum is 12.

The square root of 21441 is about 146.4274564417. The cubic root of 21441 is about 27.7810301377.

Adding to 21441 its reverse (14412), we get a palindrome (35853).

It can be divided in two parts, 2144 and 1, that added together give a triangular number (2145 = T₆₅).

The spelling of 21441 in words is "twenty-one thousand, four hundred forty-one", and thus it is an iban number.