20105405 has 4 divisors (see below), whose sum is σ = 24126492. Its totient is φ = 16084320.

The previous prime is 20105399. The next prime is 20105411. The reversal of 20105405 is 50450102.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (20105399) and next prime (20105411).

It can be written as a sum of positive squares in 2 ways, for example, as 9523396 + 10582009 = 3086^2 + 3253^2 .

It is not a de Polignac number, because 20105405 - 2⁶ = 20105341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 2010536 + ... + 2010545.

It is an arithmetic number, because the mean of its divisors is an integer number (6031623).

Almost surely, 2^20105405 is an apocalyptic number.

It is an amenable number.

20105405 is a deficient number, since it is larger than the sum of its proper divisors (4021087).

20105405 is an equidigital number, since it uses as much as digits as its factorization.

20105405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4021086.

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 20105405 is about 4483.9051060432. The cubic root of 20105405 is about 271.9177817029.

Adding to 20105405 its reverse (50450102), we get a palindrome (70555507).

The spelling of 20105405 in words is "twenty million, one hundred five thousand, four hundred five".