21008363 has 4 divisors (see below), whose sum is σ = 21017640. Its totient is φ = 20999088.

The previous prime is 21008353. The next prime is 21008371. The reversal of 21008363 is 36380012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21008363 - 2⁴ = 21008347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21008353) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1256 + ... + 6602.

It is an arithmetic number, because the mean of its divisors is an integer number (5254410).

Almost surely, 2^21008363 is an apocalyptic number.

21008363 is a deficient number, since it is larger than the sum of its proper divisors (9277).

21008363 is an equidigital number, since it uses as much as digits as its factorization.

21008363 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9276.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21008363 is about 4583.4880822361. The cubic root of 21008363 is about 275.9290364012.

Adding to 21008363 its reverse (36380012), we get a palindrome (57388375).

The spelling of 21008363 in words is "twenty-one million, eight thousand, three hundred sixty-three".