20305565 has 16 divisors (see below), whose sum is σ = 29486592. Its totient is φ = 13104384.

The previous prime is 20305559. The next prime is 20305567. The reversal of 20305565 is 56550302.

It is a cyclic number.

It is not a de Polignac number, because 20305565 - 2¹⁰ = 20304541 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 (20305567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16469 + ... + 17658.

It is an arithmetic number, because the mean of its divisors is an integer number (1842912).

Almost surely, 2^20305565 is an apocalyptic number.

It is an amenable number.

20305565 is a deficient number, since it is larger than the sum of its proper divisors (9181027).

20305565 is a wasteful number, since it uses less digits than its factorization.

20305565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34156.

The product of its (nonzero) digits is 4500, while the sum is 26.

The square root of 20305565 is about 4506.1696594780. The cubic root of 20305565 is about 272.8171657040.

Adding to 20305565 its reverse (56550302), we get a palindrome (76855867).

The spelling of 20305565 in words is "twenty million, three hundred five thousand, five hundred sixty-five".