21449 has 4 divisors (see below), whose sum is σ = 21780. Its totient is φ = 21120.

The previous prime is 21433. The next prime is 21467. The reversal of 21449 is 94412.

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 10000 + 11449 = 100^2 + 107^2 .

It is a cyclic number.

It is not a de Polignac number, because 21449 - 2⁴ = 21433 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 21449.

It is not an unprimeable number, because it can be changed into a prime (21419) 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, 32 + ... + 209.

It is an arithmetic number, because the mean of its divisors is an integer number (5445).

2²¹⁴⁴⁹ is an apocalyptic number.

It is an amenable number.

21449 is a deficient number, since it is larger than the sum of its proper divisors (331).

21449 is an equidigital number, since it uses as much as digits as its factorization.

21449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330.

The product of its digits is 288, while the sum is 20.

The square root of 21449 is about 146.4547711753. The cubic root of 21449 is about 27.7844848989.

The spelling of 21449 in words is "twenty-one thousand, four hundred forty-nine".