6561556555101 has 4 divisors (see below), whose sum is σ = 8748742073472. Its totient is φ = 4374371036732.

The previous prime is 6561556555091. The next prime is 6561556555189. The reversal of 6561556555101 is 1015556551656.

6561556555101 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6561556555101 - 2¹⁵ = 6561556522333 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561556565101) 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, 1093592759181 + ... + 1093592759186.

It is an arithmetic number, because the mean of its divisors is an integer number (2187185518368).

Almost surely, 2^{6561556555101} is an apocalyptic number.

It is an amenable number.

6561556555101 is a deficient number, since it is larger than the sum of its proper divisors (2187185518371).

6561556555101 is a wasteful number, since it uses less digits than its factorization.

6561556555101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2187185518370.

The product of its (nonzero) digits is 3375000, while the sum is 51.

The spelling of 6561556555101 in words is "six trillion, five hundred sixty-one billion, five hundred fifty-six million, five hundred fifty-five thousand, one hundred one".