668917128 has 128 divisors (see below), whose sum is σ = 1871216640. Its totient is φ = 197568000.

The previous prime is 668917127. The next prime is 668917133. The reversal of 668917128 is 821719866.

It is not an unprimeable number, because it can be changed into a prime (668917121) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2380348 + ... + 2380628.

It is an arithmetic number, because the mean of its divisors is an integer number (14618880).

Almost surely, 2^668917128 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 668917128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (935608320).

668917128 is an abundant number, since it is smaller than the sum of its proper divisors (1202299512).

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

668917128 is a wasteful number, since it uses less digits than its factorization.

668917128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499 (or 495 counting only the distinct ones).

The product of its digits is 290304, while the sum is 48.

The square root of 668917128 is about 25863.4322548265. The cubic root of 668917128 is about 874.5623402560.

The spelling of 668917128 in words is "six hundred sixty-eight million, nine hundred seventeen thousand, one hundred twenty-eight".