21066566 has 8 divisors (see below), whose sum is σ = 31651824. Its totient is φ = 10515960.

The previous prime is 21066527. The next prime is 21066581. The reversal of 21066566 is 66566012.

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 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, 7085 + ... + 9608.

It is an arithmetic number, because the mean of its divisors is an integer number (3956478).

Almost surely, 2^21066566 is an apocalyptic number.

21066566 is a deficient number, since it is larger than the sum of its proper divisors (10585258).

21066566 is a wasteful number, since it uses less digits than its factorization.

21066566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17326.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 21066566 is about 4589.8328945616. The cubic root of 21066566 is about 276.1836189746.

The spelling of 21066566 in words is "twenty-one million, sixty-six thousand, five hundred sixty-six".