21224289 has 4 divisors (see below), whose sum is σ = 28299056. Its totient is φ = 14149524.

The previous prime is 21224267. The next prime is 21224293. The reversal of 21224289 is 98242212.

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 not a de Polignac number, because 21224289 - 2¹⁷ = 21093217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21224249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3537379 + ... + 3537384.

It is an arithmetic number, because the mean of its divisors is an integer number (7074764).

Almost surely, 2^21224289 is an apocalyptic number.

It is an amenable number.

21224289 is a deficient number, since it is larger than the sum of its proper divisors (7074767).

21224289 is an equidigital number, since it uses as much as digits as its factorization.

21224289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7074766.

The product of its digits is 4608, while the sum is 30.

The square root of 21224289 is about 4606.9826350877. The cubic root of 21224289 is about 276.8711578294.

The spelling of 21224289 in words is "twenty-one million, two hundred twenty-four thousand, two hundred eighty-nine".