666761686560 has 960 divisors, whose sum is σ = 2571491349504. Its totient is φ = 162039398400.

The previous prime is 666761686553. The next prime is 666761686609. The reversal of 666761686560 is 65686167666.

It is a happy number.

It is a super-2 number, since 2×666761686560² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 2014385595 + ... + 2014385925.

Almost surely, 2^666761686560 is an apocalyptic number.

666761686560 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 666761686560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1285745674752).

666761686560 is an abundant number, since it is smaller than the sum of its proper divisors (1904729662944).

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

666761686560 is a wasteful number, since it uses less digits than its factorization.

666761686560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 639 (or 622 counting only the distinct ones).

The product of its (nonzero) digits is 78382080, while the sum is 63.

The spelling of 666761686560 in words is "six hundred sixty-six billion, seven hundred sixty-one million, six hundred eighty-six thousand, five hundred sixty".