21805103 has 4 divisors (see below), whose sum is σ = 22952760. Its totient is φ = 20657448.

The previous prime is 21805079. The next prime is 21805117. The reversal of 21805103 is 30150812.

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 21805103 - 2¹⁴ = 21788719 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808103) 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, 573800 + ... + 573837.

It is an arithmetic number, because the mean of its divisors is an integer number (5738190).

Almost surely, 2^21805103 is an apocalyptic number.

21805103 is a deficient number, since it is larger than the sum of its proper divisors (1147657).

21805103 is a wasteful number, since it uses less digits than its factorization.

21805103 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1147656.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21805103 is about 4669.5934512546. The cubic root of 21805103 is about 279.3740395878.

Adding to 21805103 its reverse (30150812), we get a palindrome (51955915).

The spelling of 21805103 in words is "twenty-one million, eight hundred five thousand, one hundred three".