21066947 has 12 divisors (see below), whose sum is σ = 23700600. Its totient is φ = 18701760.

The previous prime is 21066937. The next prime is 21066959. The reversal of 21066947 is 74966012.

It is not a de Polignac number, because 21066947 - 2⁴ = 21066931 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21066937) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 3179 + ... + 7227.

It is an arithmetic number, because the mean of its divisors is an integer number (1975050).

Almost surely, 2^21066947 is an apocalyptic number.

21066947 is a deficient number, since it is larger than the sum of its proper divisors (2633653).

21066947 is a wasteful number, since it uses less digits than its factorization.

21066947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4114 (or 4103 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 21066947 is about 4589.8743991530. The cubic root of 21066947 is about 276.1852839402.

The spelling of 21066947 in words is "twenty-one million, sixty-six thousand, nine hundred forty-seven".