20516565 has 32 divisors (see below), whose sum is σ = 33872256. Its totient is φ = 10599680.

The previous prime is 20516549. The next prime is 20516591. The reversal of 20516565 is 56561502.

It is not a de Polignac number, because 20516565 - 2⁴ = 20516549 is a prime.

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 31 ways as a sum of consecutive naturals, for example, 104047 + ... + 104243.

It is an arithmetic number, because the mean of its divisors is an integer number (1058508).

Almost surely, 2^20516565 is an apocalyptic number.

It is an amenable number.

20516565 is a deficient number, since it is larger than the sum of its proper divisors (13355691).

20516565 is a wasteful number, since it uses less digits than its factorization.

20516565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389.

The product of its (nonzero) digits is 9000, while the sum is 30.

The square root of 20516565 is about 4529.5214979068. The cubic root of 20516565 is about 273.7588808862.

The spelling of 20516565 in words is "twenty million, five hundred sixteen thousand, five hundred sixty-five".