666071864640 has 2688 divisors, whose sum is σ = 3187291161600. Its totient is φ = 131096641536.

The previous prime is 666071864639. The next prime is 666071864677. The reversal of 666071864640 is 46468170666.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 5894441224 + ... + 5894441336.

It is an arithmetic number, because the mean of its divisors is an integer number (1185748200).

Almost surely, 2^666071864640 is an apocalyptic number.

666071864640 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 666071864640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1593645580800).

666071864640 is an abundant number, since it is smaller than the sum of its proper divisors (2521219296960).

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

666071864640 is a wasteful number, since it uses less digits than its factorization.

666071864640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 160 counting only the distinct ones).

The product of its (nonzero) digits is 6967296, while the sum is 54.

The spelling of 666071864640 in words is "six hundred sixty-six billion, seventy-one million, eight hundred sixty-four thousand, six hundred forty".