66516844861566 has 96 divisors (see below), whose sum is σ = 157872623201280. Its totient is φ = 20073222619200.

The previous prime is 66516844861531. The next prime is 66516844861573.

66516844861566 is a `hidden beast` number, since 6 + 6 + 5 + 1 + 6 + 84 + 486 + 1 + 5 + 66 = 666.

66516844861566 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 66516844861494 and 66516844861503.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 126661311 + ... + 127185381.

It is an arithmetic number, because the mean of its divisors is an integer number (1644506491680).

Almost surely, 2^{66516844861566} is an apocalyptic number.

66516844861566 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 66516844861566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78936311600640).

66516844861566 is an abundant number, since it is smaller than the sum of its proper divisors (91355778339714).

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

66516844861566 is a wasteful number, since it uses less digits than its factorization.

66516844861566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 526742 (or 526739 counting only the distinct ones).

The product of its digits is 1194393600, while the sum is 72.

The spelling of 66516844861566 in words is "sixty-six trillion, five hundred sixteen billion, eight hundred forty-four million, eight hundred sixty-one thousand, five hundred sixty-six".