20108561 has 4 divisors (see below), whose sum is σ = 21936624. Its totient is φ = 18280500.

The previous prime is 20108551. The next prime is 20108591. The reversal of 20108561 is 16580102.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20108561 - 2⁶ = 20108497 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20108521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 914015 + ... + 914036.

It is an arithmetic number, because the mean of its divisors is an integer number (5484156).

Almost surely, 2^20108561 is an apocalyptic number.

It is an amenable number.

20108561 is a deficient number, since it is larger than the sum of its proper divisors (1828063).

20108561 is a wasteful number, since it uses less digits than its factorization.

20108561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1828062.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 20108561 is about 4484.2570176117. The cubic root of 20108561 is about 271.9320088493.

Adding to 20108561 its reverse (16580102), we get a palindrome (36688663).

The spelling of 20108561 in words is "twenty million, one hundred eight thousand, five hundred sixty-one".