21040566 has 16 divisors (see below), whose sum is σ = 42674688. Its totient is φ = 6914600.

The previous prime is 21040559. The next prime is 21040601. The reversal of 21040566 is 66504012.

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 7 ways as a sum of consecutive naturals, for example, 24270 + ... + 25121.

It is an arithmetic number, because the mean of its divisors is an integer number (2667168).

Almost surely, 2^21040566 is an apocalyptic number.

21040566 is an abundant number, since it is smaller than the sum of its proper divisors (21634122).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21040566 is a wasteful number, since it uses less digits than its factorization.

21040566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49467.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 21040566 is about 4586.9996729889. Note that the first 3 decimals coincide. The cubic root of 21040566 is about 276.0699518135.

Adding to 21040566 its reverse (66504012), we get a palindrome (87544578).

The spelling of 21040566 in words is "twenty-one million, forty thousand, five hundred sixty-six".