61666338716784 has 200 divisors, whose sum is σ = 179096988264480. Its totient is φ = 20484530214912.

The previous prime is 61666338716779. The next prime is 61666338716837. The reversal of 61666338716784 is 48761783366616.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 487521772 + ... + 487648244.

Almost surely, 2^{61666338716784} 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 61666338716784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89548494132240).

61666338716784 is an abundant number, since it is smaller than the sum of its proper divisors (117430649547696).

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

61666338716784 is a wasteful number, since it uses less digits than its factorization.

61666338716784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127789 (or 127774 counting only the distinct ones).

The product of its digits is 877879296, while the sum is 72.

The spelling of 61666338716784 in words is "sixty-one trillion, six hundred sixty-six billion, three hundred thirty-eight million, seven hundred sixteen thousand, seven hundred eighty-four".