21264447 has 4 divisors (see below), whose sum is σ = 28352600. Its totient is φ = 14176296.

The previous prime is 21264427. The next prime is 21264449. The reversal of 21264447 is 74446212.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21264447 - 2¹¹ = 21262399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21264449) 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, 3544072 + ... + 3544077.

It is an arithmetic number, because the mean of its divisors is an integer number (7088150).

Almost surely, 2^21264447 is an apocalyptic number.

21264447 is a deficient number, since it is larger than the sum of its proper divisors (7088153).

21264447 is an equidigital number, since it uses as much as digits as its factorization.

21264447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7088152.

The product of its digits is 10752, while the sum is 30.

The square root of 21264447 is about 4611.3389595648. The cubic root of 21264447 is about 277.0456683773.

The spelling of 21264447 in words is "twenty-one million, two hundred sixty-four thousand, four hundred forty-seven".