108921809 has 4 divisors (see below), whose sum is σ = 109270116. Its totient is φ = 108573504.

The previous prime is 108921781. The next prime is 108921811. The reversal of 108921809 is 908129801.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 908129801 = 167 ⋅5437903.

It can be written as a sum of positive squares in 2 ways, for example, as 9859600 + 99062209 = 3140^2 + 9953^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-108921809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (108921829) 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, 173684 + ... + 174309.

It is an arithmetic number, because the mean of its divisors is an integer number (27317529).

Almost surely, 2^108921809 is an apocalyptic number.

It is an amenable number.

108921809 is a deficient number, since it is larger than the sum of its proper divisors (348307).

108921809 is an equidigital number, since it uses as much as digits as its factorization.

108921809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 348306.

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 108921809 is about 10436.5611673578. The cubic root of 108921809 is about 477.5713684066.

The spelling of 108921809 in words is "one hundred eight million, nine hundred twenty-one thousand, eight hundred nine".