6561015055661 has 16 divisors (see below), whose sum is σ = 7170148789440. Its totient is φ = 5953997301120.

The previous prime is 6561015055633. The next prime is 6561015055669. The reversal of 6561015055661 is 1665505101656.

It is not a de Polignac number, because 6561015055661 - 2¹⁸ = 6561014793517 is a prime.

It is a super-2 number, since 2×6561015055661² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561015055669) 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, 45773441 + ... + 45916553.

It is an arithmetic number, because the mean of its divisors is an integer number (448134299340).

Almost surely, 2^{6561015055661} is an apocalyptic number.

It is an amenable number.

6561015055661 is a deficient number, since it is larger than the sum of its proper divisors (609133733779).

6561015055661 is a wasteful number, since it uses less digits than its factorization.

6561015055661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150476.

The product of its (nonzero) digits is 810000, while the sum is 47.

The spelling of 6561015055661 in words is "six trillion, five hundred sixty-one billion, fifteen million, fifty-five thousand, six hundred sixty-one".