21104863 has 4 divisors (see below), whose sum is σ = 22728328. Its totient is φ = 19481400.

The previous prime is 21104857. The next prime is 21104879. The reversal of 21104863 is 36840112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21104863 - 2¹³ = 21096671 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21104843) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 811713 + ... + 811738.

It is an arithmetic number, because the mean of its divisors is an integer number (5682082).

Almost surely, 2^21104863 is an apocalyptic number.

21104863 is a deficient number, since it is larger than the sum of its proper divisors (1623465).

21104863 is a wasteful number, since it uses less digits than its factorization.

21104863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1623464.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 21104863 is about 4594.0029386146. The cubic root of 21104863 is about 276.3508761218.

Adding to 21104863 its reverse (36840112), we get a palindrome (57944975).

The spelling of 21104863 in words is "twenty-one million, one hundred four thousand, eight hundred sixty-three".