20661266559 has 16 divisors (see below), whose sum is σ = 27658772064. Its totient is φ = 13719014400.

The previous prime is 20661266513. The next prime is 20661266567. The reversal of 20661266559 is 95566216602.

It is not a de Polignac number, because 20661266559 - 2²³ = 20652877951 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661266959) 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, 2627077 + ... + 2634929.

It is an arithmetic number, because the mean of its divisors is an integer number (1728673254).

Almost surely, 2^20661266559 is an apocalyptic number.

20661266559 is a deficient number, since it is larger than the sum of its proper divisors (6997505505).

20661266559 is a wasteful number, since it uses less digits than its factorization.

20661266559 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11258.

The product of its (nonzero) digits is 1166400, while the sum is 48.

The spelling of 20661266559 in words is "twenty billion, six hundred sixty-one million, two hundred sixty-six thousand, five hundred fifty-nine".