21664315406 has 8 divisors (see below), whose sum is σ = 33374756280. Its totient is φ = 10539396648.

The previous prime is 21664315363. The next prime is 21664315459. The reversal of 21664315406 is 60451346612.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21664315406.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 146380436 + ... + 146380583.

It is an arithmetic number, because the mean of its divisors is an integer number (4171844535).

Almost surely, 2^21664315406 is an apocalyptic number.

21664315406 is a deficient number, since it is larger than the sum of its proper divisors (11710440874).

21664315406 is a wasteful number, since it uses less digits than its factorization.

21664315406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292761058.

The product of its (nonzero) digits is 103680, while the sum is 38.

The spelling of 21664315406 in words is "twenty-one billion, six hundred sixty-four million, three hundred fifteen thousand, four hundred six".