66686816542464 has 216 divisors, whose sum is σ = 198978544805040. Its totient is φ = 21454454439936.

The previous prime is 66686816542399. The next prime is 66686816542481. The reversal of 66686816542464 is 46424561868666.

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

It is a junction number, because it is equal to n+sod(n) for n = 66686816542392 and 66686816542401.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 181087867 + ... + 181455749.

It is an arithmetic number, because the mean of its divisors is an integer number (921196966690).

Almost surely, 2^{66686816542464} is an apocalyptic number.

66686816542464 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66686816542464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99489272402520).

66686816542464 is an abundant number, since it is smaller than the sum of its proper divisors (132291728262576).

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

66686816542464 is a wasteful number, since it uses less digits than its factorization.

66686816542464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 370647 (or 370630 counting only the distinct ones).

The product of its digits is 1911029760, while the sum is 72.

The spelling of 66686816542464 in words is "sixty-six trillion, six hundred eighty-six billion, eight hundred sixteen million, five hundred forty-two thousand, four hundred sixty-four".