21895109 has 4 divisors (see below), whose sum is σ = 22195116. Its totient is φ = 21595104.

The previous prime is 21895073. The next prime is 21895121. The reversal of 21895109 is 90159812.

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 6646084 + 15249025 = 2578^2 + 3905^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21895109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21895169) 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 3 ways as a sum of consecutive naturals, for example, 149894 + ... + 150039.

It is an arithmetic number, because the mean of its divisors is an integer number (5548779).

Almost surely, 2^21895109 is an apocalyptic number.

It is an amenable number.

21895109 is a deficient number, since it is larger than the sum of its proper divisors (300007).

21895109 is an equidigital number, since it uses as much as digits as its factorization.

21895109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300006.

The product of its (nonzero) digits is 6480, while the sum is 35.

The square root of 21895109 is about 4679.2209821721. The cubic root of 21895109 is about 279.7579072394.

The spelling of 21895109 in words is "twenty-one million, eight hundred ninety-five thousand, one hundred nine".