21110665 has 8 divisors (see below), whose sum is σ = 26434368. Its totient is φ = 16154160.

The previous prime is 21110647. The next prime is 21110669. The reversal of 21110665 is 56601112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21110665 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21110669) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 91671 + ... + 91900.

It is an arithmetic number, because the mean of its divisors is an integer number (3304296).

Almost surely, 2^21110665 is an apocalyptic number.

It is an amenable number.

21110665 is a deficient number, since it is larger than the sum of its proper divisors (5323703).

21110665 is a wasteful number, since it uses less digits than its factorization.

21110665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183599.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21110665 is about 4594.6343706545. The cubic root of 21110665 is about 276.3761979457.

Adding to 21110665 its reverse (56601112), we get a palindrome (77711777).

The spelling of 21110665 in words is "twenty-one million, one hundred ten thousand, six hundred sixty-five".