21164065 has 32 divisors (see below), whose sum is σ = 29393280. Its totient is φ = 14490624.

The previous prime is 21164063. The next prime is 21164093. The reversal of 21164065 is 56046112.

It is a cyclic number.

It is not a de Polignac number, because 21164065 - 2¹ = 21164063 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21164063) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 118146 + ... + 118324.

It is an arithmetic number, because the mean of its divisors is an integer number (918540).

Almost surely, 2^21164065 is an apocalyptic number.

It is an amenable number.

21164065 is a deficient number, since it is larger than the sum of its proper divisors (8229215).

21164065 is a wasteful number, since it uses less digits than its factorization.

21164065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21164065 is about 4600.4418266075. The cubic root of 21164065 is about 276.6090354306.

The spelling of 21164065 in words is "twenty-one million, one hundred sixty-four thousand, sixty-five".