66555666699966 has 96 divisors (see below), whose sum is σ = 157035878064000. Its totient is φ = 20291802398784.

The previous prime is 66555666699953. The next prime is 66555666700021. The reversal of 66555666699966 is 66999666655566.

66555666699966 is a nontrivial binomial coefficient, being equal to C(11537389, 2).

It is a zygodrome in base 10.

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, 207512761 + ... + 207833243.

It is an arithmetic number, because the mean of its divisors is an integer number (1635790396500).

Almost surely, 2^{66555666699966} is an apocalyptic number.

66555666699966 is the 11537388-th triangular number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66555666699966, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78517939032000).

66555666699966 is an abundant number, since it is smaller than the sum of its proper divisors (90480211364034).

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

66555666699966 is a wasteful number, since it uses less digits than its factorization.

66555666699966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341478 (or 341475 counting only the distinct ones).

The product of its digits is 153055008000, while the sum is 90.

The spelling of 66555666699966 in words is "sixty-six trillion, five hundred fifty-five billion, six hundred sixty-six million, six hundred ninety-nine thousand, nine hundred sixty-six".