668530978128 has 120 divisors (see below), whose sum is σ = 2019666401480. Its totient is φ = 205212994560.

The previous prime is 668530978109. The next prime is 668530978139. The reversal of 668530978128 is 821879035866.

668530978128 is a `hidden beast` number, since 6 + 6 + 8 + 530 + 9 + 78 + 1 + 28 = 666.

668530978128 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 538611264 + 667992366864 = 23208^2 + 817308^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 363978 + ... + 1212246.

Almost surely, 2^668530978128 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 668530978128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1009833200740).

668530978128 is an abundant number, since it is smaller than the sum of its proper divisors (1351135423352).

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

668530978128 is a wasteful number, since it uses less digits than its factorization.

668530978128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 848717 (or 848708 counting only the distinct ones).

The product of its (nonzero) digits is 34836480, while the sum is 63.

The spelling of 668530978128 in words is "six hundred sixty-eight billion, five hundred thirty million, nine hundred seventy-eight thousand, one hundred twenty-eight".