26563655636561 has 16 divisors (see below), whose sum is σ = 26836013393280. Its totient is φ = 26291580514560.

The previous prime is 26563655636537. The next prime is 26563655636563. The reversal of 26563655636561 is 16563655636562.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-26563655636561 is a prime.

It is a super-5 number, since 5×26563655636561⁵ (a number of 68 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (26563655636563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1926431255 + ... + 1926445043.

It is an arithmetic number, because the mean of its divisors is an integer number (1677250837080).

Almost surely, 2^{26563655636561} is an apocalyptic number.

It is an amenable number.

26563655636561 is a deficient number, since it is larger than the sum of its proper divisors (272357756719).

26563655636561 is a wasteful number, since it uses less digits than its factorization.

26563655636561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22616.

The product of its digits is 524880000, while the sum is 65.

Subtracting from 26563655636561 its reverse (16563655636562), we obtain a palindrome (9999999999999).

The spelling of 26563655636561 in words is "twenty-six trillion, five hundred sixty-three billion, six hundred fifty-five million, six hundred thirty-six thousand, five hundred sixty-one".