21643105 has 16 divisors (see below), whose sum is σ = 28801728. Its totient is φ = 15480000.

The previous prime is 21643103. The next prime is 21643117. The reversal of 21643105 is 50134612.

It is not a de Polignac number, because 21643105 - 2¹ = 21643103 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21643103) 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 15 ways as a sum of consecutive naturals, for example, 130 + ... + 6580.

It is an arithmetic number, because the mean of its divisors is an integer number (1800108).

Almost surely, 2^21643105 is an apocalyptic number.

It is an amenable number.

21643105 is a deficient number, since it is larger than the sum of its proper divisors (7158623).

21643105 is a wasteful number, since it uses less digits than its factorization.

21643105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6528.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21643105 is about 4652.2150638164. The cubic root of 21643105 is about 278.6804621867.

Adding to 21643105 its reverse (50134612), we get a palindrome (71777717).

The spelling of 21643105 in words is "twenty-one million, six hundred forty-three thousand, one hundred five".