66684435840 has 480 divisors, whose sum is σ = 261784187280. Its totient is φ = 16164403200.

The previous prime is 66684435827. The next prime is 66684435847. The reversal of 66684435840 is 4853448666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66684435847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 6267325 + ... + 6277955.

Almost surely, 2^66684435840 is an apocalyptic number.

66684435840 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 66684435840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130892093640).

66684435840 is an abundant number, since it is smaller than the sum of its proper divisors (195099751440).

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

66684435840 is a wasteful number, since it uses less digits than its factorization.

66684435840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10684 (or 10652 counting only the distinct ones).

The product of its (nonzero) digits is 13271040, while the sum is 54.

The spelling of 66684435840 in words is "sixty-six billion, six hundred eighty-four million, four hundred thirty-five thousand, eight hundred forty".