21766646566 has 8 divisors (see below), whose sum is σ = 37314251280. Its totient is φ = 9328562808.

The previous prime is 21766646549. The next prime is 21766646581. The reversal of 21766646566 is 66564666712.

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

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, 777380221 + ... + 777380248.

It is an arithmetic number, because the mean of its divisors is an integer number (4664281410).

Almost surely, 2^21766646566 is an apocalyptic number.

21766646566 is a deficient number, since it is larger than the sum of its proper divisors (15547604714).

21766646566 is a wasteful number, since it uses less digits than its factorization.

21766646566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1554760478.

The product of its digits is 13063680, while the sum is 55.

The spelling of 21766646566 in words is "twenty-one billion, seven hundred sixty-six million, six hundred forty-six thousand, five hundred sixty-six".