668987557056 has 1344 divisors, whose sum is σ = 2644093670400. Its totient is φ = 161063976960.

The previous prime is 668987557033. The next prime is 668987557057. The reversal of 668987557056 is 650755789866.

It is a happy number.

668987557056 is a `hidden beast` number, since 6 + 68 + 9 + 8 + 7 + 557 + 0 + 5 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (1344).

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

It is not an unprimeable number, because it can be changed into a prime (668987557057) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 2871191116 + ... + 2871191348.

It is an arithmetic number, because the mean of its divisors is an integer number (1967331600).

Almost surely, 2^668987557056 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 668987557056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1322046835200).

668987557056 is an abundant number, since it is smaller than the sum of its proper divisors (1975106113344).

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

668987557056 is a wasteful number, since it uses less digits than its factorization.

668987557056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355 (or 308 counting only the distinct ones).

The product of its (nonzero) digits is 762048000, while the sum is 72.

The spelling of 668987557056 in words is "six hundred sixty-eight billion, nine hundred eighty-seven million, five hundred fifty-seven thousand, fifty-six".