20565548639 has 16 divisors (see below), whose sum is σ = 21431625600. Its totient is φ = 19718094816.

The previous prime is 20565548551. The next prime is 20565548687. The reversal of 20565548639 is 93684556502.

It is a cyclic number.

It is not a de Polignac number, because 20565548639 - 2⁸ = 20565548383 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 (20562548639) 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, 1854092 + ... + 1865150.

It is an arithmetic number, because the mean of its divisors is an integer number (1339476600).

Almost surely, 2^20565548639 is an apocalyptic number.

20565548639 is a deficient number, since it is larger than the sum of its proper divisors (866076961).

20565548639 is a wasteful number, since it uses less digits than its factorization.

20565548639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11894.

The product of its (nonzero) digits is 7776000, while the sum is 53.

The spelling of 20565548639 in words is "twenty billion, five hundred sixty-five million, five hundred forty-eight thousand, six hundred thirty-nine".