21664106 has 8 divisors (see below), whose sum is σ = 32554980. Its totient is φ = 10812448.

The previous prime is 21664081. The next prime is 21664109. The reversal of 21664106 is 60146612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 15928081 + 5736025 = 3991^2 + 2395^2 .

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21664109) 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 3 ways as a sum of consecutive naturals, for example, 8381 + ... + 10656.

Almost surely, 2^21664106 is an apocalyptic number.

21664106 is a deficient number, since it is larger than the sum of its proper divisors (10890874).

21664106 is a wasteful number, since it uses less digits than its factorization.

21664106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19608.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 21664106 is about 4654.4716134058. The cubic root of 21664106 is about 278.7705705827.

The spelling of 21664106 in words is "twenty-one million, six hundred sixty-four thousand, one hundred six".