66791639715840 has 2912 divisors, whose sum is σ = 271597894089984. Its totient is φ = 15651333734400.

The previous prime is 66791639715817. The next prime is 66791639715847. The reversal of 66791639715840 is 4851793619766.

66791639715840 is a `hidden beast` number, since 6 + 6 + 7 + 9 + 1 + 6 + 39 + 7 + 1 + 584 + 0 = 666.

It is a super-2 number, since 2×66791639715840² (a number of 28 digits) contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (66791639715847) by changing a digit.

It is a polite number, since it can be written in 223 ways as a sum of consecutive naturals, for example, 442328739765 + ... + 442328739915.

Almost surely, 2^{66791639715840} is an apocalyptic number.

66791639715840 is a gapful number since it is divisible by the number (60) 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 66791639715840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135798947044992).

66791639715840 is an abundant number, since it is smaller than the sum of its proper divisors (204806254374144).

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

66791639715840 is a wasteful number, since it uses less digits than its factorization.

66791639715840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 307 (or 270 counting only the distinct ones).

The product of its (nonzero) digits is 411505920, while the sum is 72.

The spelling of 66791639715840 in words is "sixty-six trillion, seven hundred ninety-one billion, six hundred thirty-nine million, seven hundred fifteen thousand, eight hundred forty".