20641864559 has 4 divisors (see below), whose sum is σ = 21856091904. Its totient is φ = 19427637216.

The previous prime is 20641864543. The next prime is 20641864571. The reversal of 20641864559 is 95546814602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20641864559 - 2⁴ = 20641864543 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 (20641864589) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 607113647 + ... + 607113680.

It is an arithmetic number, because the mean of its divisors is an integer number (5464022976).

Almost surely, 2^20641864559 is an apocalyptic number.

20641864559 is a deficient number, since it is larger than the sum of its proper divisors (1214227345).

20641864559 is a wasteful number, since it uses less digits than its factorization.

20641864559 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1214227344.

The product of its (nonzero) digits is 2073600, while the sum is 50.

The spelling of 20641864559 in words is "twenty billion, six hundred forty-one million, eight hundred sixty-four thousand, five hundred fifty-nine".