21665089 has 8 divisors (see below), whose sum is σ = 22999680. Its totient is φ = 20337216.

The previous prime is 21665087. The next prime is 21665093. The reversal of 21665089 is 98056612.

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

It is a cyclic number.

It is not a de Polignac number, because 21665089 - 2¹ = 21665087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21665087) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6012 + ... + 8914.

It is an arithmetic number, because the mean of its divisors is an integer number (2874960).

Almost surely, 2^21665089 is an apocalyptic number.

It is an amenable number.

21665089 is a deficient number, since it is larger than the sum of its proper divisors (1334591).

21665089 is a wasteful number, since it uses less digits than its factorization.

21665089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3359.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 21665089 is about 4654.5772095863. The cubic root of 21665089 is about 278.7747868860.

The spelling of 21665089 in words is "twenty-one million, six hundred sixty-five thousand, eighty-nine".