21164105 has 4 divisors (see below), whose sum is σ = 25396932. Its totient is φ = 16931280.

The previous prime is 21164093. The next prime is 21164107. The reversal of 21164105 is 50146112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12823561 + 8340544 = 3581^2 + 2888^2 .

It is not a de Polignac number, because 21164105 - 2¹⁸ = 20901961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21164107) 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, 2116406 + ... + 2116415.

It is an arithmetic number, because the mean of its divisors is an integer number (6349233).

Almost surely, 2^21164105 is an apocalyptic number.

It is an amenable number.

21164105 is a deficient number, since it is larger than the sum of its proper divisors (4232827).

21164105 is an equidigital number, since it uses as much as digits as its factorization.

21164105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4232826.

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

The square root of 21164105 is about 4600.4461740140. The cubic root of 21164105 is about 276.6092096939.

The spelling of 21164105 in words is "twenty-one million, one hundred sixty-four thousand, one hundred five".