21164365 has 4 divisors (see below), whose sum is σ = 25397244. Its totient is φ = 16931488.

The previous prime is 21164357. The next prime is 21164401. The reversal of 21164365 is 56346112.

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 5148361 + 16016004 = 2269^2 + 4002^2 .

It is a cyclic number.

It is not a de Polignac number, because 21164365 - 2³ = 21164357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2116432 + ... + 2116441.

It is an arithmetic number, because the mean of its divisors is an integer number (6349311).

Almost surely, 2^21164365 is an apocalyptic number.

It is an amenable number.

21164365 is a deficient number, since it is larger than the sum of its proper divisors (4232879).

21164365 is an equidigital number, since it uses as much as digits as its factorization.

21164365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4232878.

The product of its digits is 4320, while the sum is 28.

The square root of 21164365 is about 4600.4744320559. The cubic root of 21164365 is about 276.6103423994.

The spelling of 21164365 in words is "twenty-one million, one hundred sixty-four thousand, three hundred sixty-five".