21404449 has 4 divisors (see below), whose sum is σ = 23350320. Its totient is φ = 19458580.

The previous prime is 21404437. The next prime is 21404459. The reversal of 21404449 is 94440412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21404449 - 2⁵ = 21404417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21404459) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 972919 + ... + 972940.

It is an arithmetic number, because the mean of its divisors is an integer number (5837580).

Almost surely, 2^21404449 is an apocalyptic number.

It is an amenable number.

21404449 is a deficient number, since it is larger than the sum of its proper divisors (1945871).

21404449 is a wasteful number, since it uses less digits than its factorization.

21404449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1945870.

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 21404449 is about 4626.4942451061. The cubic root of 21404449 is about 277.6523482365.

The spelling of 21404449 in words is "twenty-one million, four hundred four thousand, four hundred forty-nine".