21066003 has 24 divisors (see below), whose sum is σ = 36608000. Its totient is φ = 11403504.

The previous prime is 21065971. The next prime is 21066007. The reversal of 21066003 is 30066012.

It is a happy number.

21066003 is a `hidden beast` number, since 2 + 1 + 0 + 660 + 0 + 3 = 666.

It is not a de Polignac number, because 21066003 - 2⁵ = 21065971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21066007) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7603 + ... + 9996.

Almost surely, 2^21066003 is an apocalyptic number.

21066003 is a deficient number, since it is larger than the sum of its proper divisors (15541997).

21066003 is a wasteful number, since it uses less digits than its factorization.

21066003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17631 (or 17628 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21066003 is about 4589.7715629430. The cubic root of 21066003 is about 276.1811586343.

Subtracting 21066003 from its reverse (30066012), we obtain a palindrome (9000009).

The spelling of 21066003 in words is "twenty-one million, sixty-six thousand, three".