66519857456640 has 2560 divisors, whose sum is σ = 294341160960000. Its totient is φ = 14202136166400.

The previous prime is 66519857456623. The next prime is 66519857456693. The reversal of 66519857456640 is 4665475891566.

It is a happy number.

66519857456640 is a `hidden beast` number, since 6 + 6 + 5 + 1 + 9 + 8 + 57 + 4 + 566 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (2560).

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 255 ways as a sum of consecutive naturals, for example, 21313634280 + ... + 21313637400.

It is an arithmetic number, because the mean of its divisors is an integer number (114977016000).

Almost surely, 2^{66519857456640} is an apocalyptic number.

66519857456640 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 66519857456640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147170580480000).

66519857456640 is an abundant number, since it is smaller than the sum of its proper divisors (227821303503360).

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

66519857456640 is a wasteful number, since it uses less digits than its factorization.

66519857456640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3234 (or 3198 counting only the distinct ones).

The product of its (nonzero) digits is 1306368000, while the sum is 72.

The spelling of 66519857456640 in words is "sixty-six trillion, five hundred nineteen billion, eight hundred fifty-seven million, four hundred fifty-six thousand, six hundred forty".