21044663 has 6 divisors (see below), whose sum is σ = 21265392. Its totient is φ = 20826200.

The previous prime is 21044627. The next prime is 21044687. The reversal of 21044663 is 36644012.

It is not a de Polignac number, because 21044663 - 2⁸ = 21044407 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 (21044063) 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 5 ways as a sum of consecutive naturals, for example, 9170 + ... + 11232.

It is an arithmetic number, because the mean of its divisors is an integer number (3544232).

Almost surely, 2^21044663 is an apocalyptic number.

21044663 is a deficient number, since it is larger than the sum of its proper divisors (220729).

21044663 is an equidigital number, since it uses as much as digits as its factorization.

21044663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2265 (or 2164 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 21044663 is about 4587.4462394670. The cubic root of 21044663 is about 276.0878693478.

Adding to 21044663 its reverse (36644012), we get a palindrome (57688675).

The spelling of 21044663 in words is "twenty-one million, forty-four thousand, six hundred sixty-three".