21664046 has 4 divisors (see below), whose sum is σ = 32496072. Its totient is φ = 10832022.

The previous prime is 21664037. The next prime is 21664051. The reversal of 21664046 is 64046612.

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

It is a congruent number.

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, 5416010 + ... + 5416013.

It is an arithmetic number, because the mean of its divisors is an integer number (8124018).

Almost surely, 2^21664046 is an apocalyptic number.

21664046 is a deficient number, since it is larger than the sum of its proper divisors (10832026).

21664046 is a wasteful number, since it uses less digits than its factorization.

21664046 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10832025.

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 21664046 is about 4654.4651679865. The cubic root of 21664046 is about 278.7703132254.

The spelling of 21664046 in words is "twenty-one million, six hundred sixty-four thousand, forty-six".