66699560881280 has 128 divisors (see below), whose sum is σ = 163565639420400. Its totient is φ = 25993579069440.

The previous prime is 66699560881211. The next prime is 66699560881307. The reversal of 66699560881280 is 8218806599666.

It can be written as a sum of positive squares in 8 ways, for example, as 18031301483584 + 48668259397696 = 4246328^2 + 6976264^2 .

It is a tau number, because it is divible by the number of its divisors (128).

It is a Smith number, since the sum of its digits (74) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 66699560881198 and 66699560881207.

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 15 ways as a sum of consecutive naturals, for example, 17500016 + ... + 20967824.

Almost surely, 2^{66699560881280} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66699560881280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81782819710200).

66699560881280 is an abundant number, since it is smaller than the sum of its proper divisors (96866078539120).

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

66699560881280 is a wasteful number, since it uses less digits than its factorization.

66699560881280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3468602 (or 3468590 counting only the distinct ones).

The product of its (nonzero) digits is 537477120, while the sum is 74.

The spelling of 66699560881280 in words is "sixty-six trillion, six hundred ninety-nine billion, five hundred sixty million, eight hundred eighty-one thousand, two hundred eighty".