21664466 has 4 divisors (see below), whose sum is σ = 32496702. Its totient is φ = 10832232.

The previous prime is 21664457. The next prime is 21664471. The reversal of 21664466 is 66446612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20967241 + 697225 = 4579^2 + 835^2 .

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 as a sum of consecutive naturals, namely, 5416115 + ... + 5416118.

Almost surely, 2^21664466 is an apocalyptic number.

21664466 is a deficient number, since it is larger than the sum of its proper divisors (10832236).

21664466 is a wasteful number, since it uses less digits than its factorization.

21664466 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10832235.

The product of its digits is 41472, while the sum is 35.

The square root of 21664466 is about 4654.5102857336. The cubic root of 21664466 is about 278.7721147168.

The spelling of 21664466 in words is "twenty-one million, six hundred sixty-four thousand, four hundred sixty-six".