665731978560 has 336 divisors, whose sum is σ = 2503855141632. Its totient is φ = 161011814400.

The previous prime is 665731978547. The next prime is 665731978577. The reversal of 665731978560 is 65879137566.

665731978560 is a `hidden beast` number, since 6 + 6 + 57 + 3 + 19 + 7 + 8 + 560 = 666.

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 47 ways as a sum of consecutive naturals, for example, 13629702 + ... + 13678458.

Almost surely, 2^665731978560 is an apocalyptic number.

665731978560 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 665731978560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1251927570816).

665731978560 is an abundant number, since it is smaller than the sum of its proper divisors (1838123163072).

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

665731978560 is a wasteful number, since it uses less digits than its factorization.

665731978560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49222 (or 49209 counting only the distinct ones).

The product of its (nonzero) digits is 57153600, while the sum is 63.

The spelling of 665731978560 in words is "six hundred sixty-five billion, seven hundred thirty-one million, nine hundred seventy-eight thousand, five hundred sixty".