21204536 has 8 divisors (see below), whose sum is σ = 39758520. Its totient is φ = 10602264.

The previous prime is 21204509. The next prime is 21204553. The reversal of 21204536 is 63540212.

It is a tau number, because it is divible by the number of its divisors (8).

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 as a sum of consecutive naturals, namely, 1325276 + ... + 1325291.

It is an arithmetic number, because the mean of its divisors is an integer number (4969815).

Almost surely, 2^21204536 is an apocalyptic number.

It is an amenable number.

21204536 is a deficient number, since it is larger than the sum of its proper divisors (18553984).

21204536 is a wasteful number, since it uses less digits than its factorization.

21204536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2650573 (or 2650569 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21204536 is about 4604.8383250664. The cubic root of 21204536 is about 276.7852384456.

Adding to 21204536 its reverse (63540212), we get a palindrome (84744748).

The spelling of 21204536 in words is "twenty-one million, two hundred four thousand, five hundred thirty-six".