65561266566 has 64 divisors (see below), whose sum is σ = 147938562240. Its totient is φ = 21517747200.

The previous prime is 65561266559. The next prime is 65561266571. The reversal of 65561266566 is 66566216556.

65561266566 is a `hidden beast` number, since 6 + 5 + 5 + 6 + 12 + 66 + 566 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2355306 + ... + 2382978.

It is an arithmetic number, because the mean of its divisors is an integer number (2311540035).

Almost surely, 2^65561266566 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65561266566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (73969281120).

65561266566 is an abundant number, since it is smaller than the sum of its proper divisors (82377295674).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

65561266566 is a wasteful number, since it uses less digits than its factorization.

65561266566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28358 (or 28352 counting only the distinct ones).

The product of its digits is 11664000, while the sum is 54.

The spelling of 65561266566 in words is "sixty-five billion, five hundred sixty-one million, two hundred sixty-six thousand, five hundred sixty-six".