26561216563 has 4 divisors (see below), whose sum is σ = 30355676080. Its totient is φ = 22766757048.

The previous prime is 26561216503. The next prime is 26561216639. The reversal of 26561216563 is 36561216562.

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

It is not a de Polignac number, because 26561216563 - 2³³ = 17971281971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (26561216503) 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, 1897229748 + ... + 1897229761.

It is an arithmetic number, because the mean of its divisors is an integer number (7588919020).

Almost surely, 2^26561216563 is an apocalyptic number.

26561216563 is a deficient number, since it is larger than the sum of its proper divisors (3794459517).

26561216563 is an equidigital number, since it uses as much as digits as its factorization.

26561216563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3794459516.

The product of its digits is 388800, while the sum is 43.

Subtracting 26561216563 from its reverse (36561216562), we obtain a palindrome (9999999999).

The spelling of 26561216563 in words is "twenty-six billion, five hundred sixty-one million, two hundred sixteen thousand, five hundred sixty-three".