21805106 has 8 divisors (see below), whose sum is σ = 33121920. Its totient is φ = 10764468.

The previous prime is 21805079. The next prime is 21805117. The reversal of 21805106 is 60150812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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, 68846 + ... + 69161.

It is an arithmetic number, because the mean of its divisors is an integer number (4140240).

Almost surely, 2^21805106 is an apocalyptic number.

21805106 is a deficient number, since it is larger than the sum of its proper divisors (11316814).

21805106 is a wasteful number, since it uses less digits than its factorization.

21805106 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138088.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 21805106 is about 4669.5937724817. The cubic root of 21805106 is about 279.3740524002.

Adding to 21805106 its reverse (60150812), we get a palindrome (81955918).

The spelling of 21805106 in words is "twenty-one million, eight hundred five thousand, one hundred six".