20005605 has 12 divisors (see below), whose sum is σ = 34676460. Its totient is φ = 10669632.

The previous prime is 20005603. The next prime is 20005637. The reversal of 20005605 is 50650002.

It can be written as a sum of positive squares in 2 ways, for example, as 10751841 + 9253764 = 3279^2 + 3042^2 .

It is not a de Polignac number, because 20005605 - 2¹ = 20005603 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20005603) 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 11 ways as a sum of consecutive naturals, for example, 222240 + ... + 222329.

It is an arithmetic number, because the mean of its divisors is an integer number (2889705).

Almost surely, 2^20005605 is an apocalyptic number.

It is an amenable number.

20005605 is a deficient number, since it is larger than the sum of its proper divisors (14670855).

20005605 is a wasteful number, since it uses less digits than its factorization.

20005605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 444580 (or 444577 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 20005605 is about 4472.7625691512. The cubic root of 20005605 is about 271.4671164756.

Adding to 20005605 its reverse (50650002), we get a palindrome (70655607).

The spelling of 20005605 in words is "twenty million, five thousand, six hundred five".