21363605 has 16 divisors (see below), whose sum is σ = 26308800. Its totient is φ = 16648320.

The previous prime is 21363599. The next prime is 21363607. The reversal of 21363605 is 50636312.

It is not a de Polignac number, because 21363605 - 2¹² = 21359509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21363607) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40745 + ... + 41265.

It is an arithmetic number, because the mean of its divisors is an integer number (1644300).

Almost surely, 2^21363605 is an apocalyptic number.

It is an amenable number.

21363605 is a deficient number, since it is larger than the sum of its proper divisors (4945195).

21363605 is a wasteful number, since it uses less digits than its factorization.

21363605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724.

The product of its (nonzero) digits is 3240, while the sum is 26.

The square root of 21363605 is about 4622.0779958802. The cubic root of 21363605 is about 277.4756302491.

Adding to 21363605 its reverse (50636312), we get a palindrome (71999917).

The spelling of 21363605 in words is "twenty-one million, three hundred sixty-three thousand, six hundred five".