66991992238080 has 2496 divisors, whose sum is σ = 310589886996480. Its totient is φ = 12956781772800.

The previous prime is 66991992238043. The next prime is 66991992238103. The reversal of 66991992238080 is 8083229919966.

66991992238080 is a `hidden beast` number, since 6 + 69 + 9 + 1 + 99 + 22 + 380 + 80 = 666.

It is a tau number, because it is divible by the number of its divisors (2496).

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 191 ways as a sum of consecutive naturals, for example, 9879364290 + ... + 9879371070.

It is an arithmetic number, because the mean of its divisors is an integer number (124435050880).

Almost surely, 2^{66991992238080} is an apocalyptic number.

66991992238080 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 66991992238080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (155294943498240).

66991992238080 is an abundant number, since it is smaller than the sum of its proper divisors (243597894758400).

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

66991992238080 is a wasteful number, since it uses less digits than its factorization.

66991992238080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6886 (or 6861 counting only the distinct ones).

The product of its (nonzero) digits is 181398528, while the sum is 72.

The spelling of 66991992238080 in words is "sixty-six trillion, nine hundred ninety-one billion, nine hundred ninety-two million, two hundred thirty-eight thousand, eighty".