21066647 has 8 divisors (see below), whose sum is σ = 24157056. Its totient is φ = 17996472.

The previous prime is 21066641. The next prime is 21066677. The reversal of 21066647 is 74666012.

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

It is a cyclic number.

It is not a de Polignac number, because 21066647 - 2¹² = 21062551 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21066641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2753 + ... + 7050.

It is an arithmetic number, because the mean of its divisors is an integer number (3019632).

Almost surely, 2^21066647 is an apocalyptic number.

21066647 is a deficient number, since it is larger than the sum of its proper divisors (3090409).

21066647 is an equidigital number, since it uses as much as digits as its factorization.

21066647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10117.

The product of its (nonzero) digits is 12096, while the sum is 32.

The square root of 21066647 is about 4589.8417184038. The cubic root of 21066647 is about 276.1839729453.

The spelling of 21066647 in words is "twenty-one million, sixty-six thousand, six hundred forty-seven".