21664711 has 8 divisors (see below), whose sum is σ = 22632480. Its totient is φ = 20711712.

The previous prime is 21664703. The next prime is 21664717. The reversal of 21664711 is 11746612.

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 21664711 - 2³ = 21664703 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21664711.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664717) 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 7 ways as a sum of consecutive naturals, for example, 640 + ... + 6613.

It is an arithmetic number, because the mean of its divisors is an integer number (2829060).

Almost surely, 2^21664711 is an apocalyptic number.

21664711 is a deficient number, since it is larger than the sum of its proper divisors (967769).

21664711 is a wasteful number, since it uses less digits than its factorization.

21664711 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7385.

The product of its digits is 2016, while the sum is 28.

The square root of 21664711 is about 4654.5366042174. The cubic root of 21664711 is about 278.7731655760.

The spelling of 21664711 in words is "twenty-one million, six hundred sixty-four thousand, seven hundred eleven".