21104663 has 4 divisors (see below), whose sum is σ = 21832440. Its totient is φ = 20376888.

The previous prime is 21104647. The next prime is 21104669. The reversal of 21104663 is 36640112.

It is a happy number.

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 21104663 - 2⁴ = 21104647 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 (21104669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 363845 + ... + 363902.

It is an arithmetic number, because the mean of its divisors is an integer number (5458110).

Almost surely, 2^21104663 is an apocalyptic number.

21104663 is a deficient number, since it is larger than the sum of its proper divisors (727777).

21104663 is an equidigital number, since it uses as much as digits as its factorization.

21104663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727776.

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

The square root of 21104663 is about 4593.9811710541. The cubic root of 21104663 is about 276.3500031737.

Adding to 21104663 its reverse (36640112), we get a palindrome (57744775).

The spelling of 21104663 in words is "twenty-one million, one hundred four thousand, six hundred sixty-three".