21112665 has 16 divisors (see below), whose sum is σ = 38606208. Its totient is φ = 9651456.

The previous prime is 21112639. The next prime is 21112673. The reversal of 21112665 is 56621112.

It is not a de Polignac number, because 21112665 - 2⁵ = 21112633 is a prime.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 100432 + ... + 100641.

It is an arithmetic number, because the mean of its divisors is an integer number (2412888).

Almost surely, 2^21112665 is an apocalyptic number.

It is an amenable number.

21112665 is a deficient number, since it is larger than the sum of its proper divisors (17493543).

21112665 is a wasteful number, since it uses less digits than its factorization.

21112665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201088.

The product of its digits is 720, while the sum is 24.

The square root of 21112665 is about 4594.8520106746. The cubic root of 21112665 is about 276.3849255240.

Adding to 21112665 its reverse (56621112), we get a palindrome (77733777).

The spelling of 21112665 in words is "twenty-one million, one hundred twelve thousand, six hundred sixty-five".