2661543163566 has 192 divisors, whose sum is σ = 6697740082176. Its totient is φ = 748185984000.

The previous prime is 2661543163561. The next prime is 2661543163589. The reversal of 2661543163566 is 6653613451662.

2661543163566 is a `hidden beast` number, since 2 + 6 + 6 + 1 + 543 + 1 + 6 + 35 + 66 = 666.

It is a super-2 number, since 2×2661543163566² (a number of 26 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2661543163561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2435080116 + ... + 2435081208.

It is an arithmetic number, because the mean of its divisors is an integer number (34884062928).

Almost surely, 2^{2661543163566} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2661543163566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3348870041088).

2661543163566 is an abundant number, since it is smaller than the sum of its proper divisors (4036196918610).

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

2661543163566 is a wasteful number, since it uses less digits than its factorization.

2661543163566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2367 (or 2364 counting only the distinct ones).

The product of its digits is 13996800, while the sum is 54.

The spelling of 2661543163566 in words is "two trillion, six hundred sixty-one billion, five hundred forty-three million, one hundred sixty-three thousand, five hundred sixty-six".