21104665 has 16 divisors (see below), whose sum is σ = 26085888. Its totient is φ = 16384896.

The previous prime is 21104647. The next prime is 21104669. The reversal of 21104665 is 56640112.

It is a cyclic number.

It is not a de Polignac number, because 21104665 - 2¹⁷ = 20973593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21104669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24024 + ... + 24886.

It is an arithmetic number, because the mean of its divisors is an integer number (1630368).

Almost surely, 2^21104665 is an apocalyptic number.

It is an amenable number.

21104665 is a deficient number, since it is larger than the sum of its proper divisors (4981223).

21104665 is an equidigital number, since it uses as much as digits as its factorization.

21104665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1008.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21104665 is about 4593.9813887303. The cubic root of 21104665 is about 276.3500119032.

Adding to 21104665 its reverse (56640112), we get a palindrome (77744777).

The spelling of 21104665 in words is "twenty-one million, one hundred four thousand, six hundred sixty-five".