21066004 has 12 divisors (see below), whose sum is σ = 36911700. Its totient is φ = 10519808.

The previous prime is 21065971. The next prime is 21066007. The reversal of 21066004 is 40066012.

It can be written as a sum of positive squares in 2 ways, for example, as 2160900 + 18905104 = 1470^2 + 4348^2 .

It is a congruent 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 3 ways as a sum of consecutive naturals, for example, 882 + ... + 6550.

It is an arithmetic number, because the mean of its divisors is an integer number (3075975).

Almost surely, 2^21066004 is an apocalyptic number.

It is an amenable number.

21066004 is a deficient number, since it is larger than the sum of its proper divisors (15845696).

21066004 is a wasteful number, since it uses less digits than its factorization.

21066004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6602 (or 6600 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21066004 is about 4589.7716718809. The cubic root of 21066004 is about 276.1811630044.

The spelling of 21066004 in words is "twenty-one million, sixty-six thousand, four".