66545555554566 has 144 divisors (see below), whose sum is σ = 158829850251072. Its totient is φ = 20120977055520.

The previous prime is 66545555554487. The next prime is 66545555554609.

It is a happy number.

66545555554566 is a `hidden beast` number, since 6 + 6 + 5 + 4 + 5 + 5 + 5 + 5 + 5 + 54 + 566 = 666.

66545555554566 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 66545555554494 and 66545555554503.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2816492845 + ... + 2816516471.

It is an arithmetic number, because the mean of its divisors is an integer number (1102985071188).

Almost surely, 2^{66545555554566} is an apocalyptic number.

66545555554566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 66545555554566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (79414925125536).

66545555554566 is an abundant number, since it is smaller than the sum of its proper divisors (92284294696506).

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

66545555554566 is a wasteful number, since it uses less digits than its factorization.

66545555554566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26447 (or 26433 counting only the distinct ones).

The product of its digits is 8100000000, while the sum is 72.

The spelling of 66545555554566 in words is "sixty-six trillion, five hundred forty-five billion, five hundred fifty-five million, five hundred fifty-four thousand, five hundred sixty-six".