21104855 has 4 divisors (see below), whose sum is σ = 25325832. Its totient is φ = 16883880.

The previous prime is 21104851. The next prime is 21104857. The reversal of 21104855 is 55840112.

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

It is not a de Polignac number, because 21104855 - 2² = 21104851 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 (21104851) 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, 2110481 + ... + 2110490.

It is an arithmetic number, because the mean of its divisors is an integer number (6331458).

Almost surely, 2^21104855 is an apocalyptic number.

21104855 is a deficient number, since it is larger than the sum of its proper divisors (4220977).

21104855 is an equidigital number, since it uses as much as digits as its factorization.

21104855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4220976.

The product of its (nonzero) digits is 1600, while the sum is 26.

The square root of 21104855 is about 4594.0020679142. The cubic root of 21104855 is about 276.3508412040.

Adding to 21104855 its reverse (55840112), we get a palindrome (76944967).

The spelling of 21104855 in words is "twenty-one million, one hundred four thousand, eight hundred fifty-five".