666406771236864 has 2688 divisors, whose sum is σ = 2437532919005184. Its totient is φ = 177916870656000.

The previous prime is 666406771236841. The next prime is 666406771236893. The reversal of 666406771236864 is 468632177604666.

It is a tau number, because it is divible by the number of its divisors (2688).

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

It is a junction number, because it is equal to n+sod(n) for n = 666406771236792 and 666406771236801.

It is an unprimeable number.

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 191 ways as a sum of consecutive naturals, for example, 3382775488414 + ... + 3382775488610.

It is an arithmetic number, because the mean of its divisors is an integer number (906820282368).

Almost surely, 2^{666406771236864} is an apocalyptic number.

666406771236864 is a gapful number since it is divisible by the number (64) 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 666406771236864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1218766459502592).

666406771236864 is an abundant number, since it is smaller than the sum of its proper divisors (1771126147768320).

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

666406771236864 is a wasteful number, since it uses less digits than its factorization.

666406771236864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 508 (or 472 counting only the distinct ones).

The product of its (nonzero) digits is 1755758592, while the sum is 72.

The spelling of 666406771236864 in words is "six hundred sixty-six trillion, four hundred six billion, seven hundred seventy-one million, two hundred thirty-six thousand, eight hundred sixty-four".