668928 has 72 divisors (see below), whose sum is σ = 1945888. Its totient is φ = 202752.

The previous prime is 668903. The next prime is 668929. The reversal of 668928 is 829866.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668929) by changing a digit.

668928 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9951 + ... + 10017.

2⁶⁶⁸⁹²⁸ 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 668928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (972944).

668928 is an abundant number, since it is smaller than the sum of its proper divisors (1276960).

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

668928 is a wasteful number, since it uses less digits than its factorization.

668928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99 (or 85 counting only the distinct ones).

The product of its digits is 41472, while the sum is 39.

The square root of 668928 is about 817.8801868245. The cubic root of 668928 is about 87.4567078357.

It can be divided in two parts, 668 and 928, that added together give a triangular number (1596 = T₅₆).

The spelling of 668928 in words is "six hundred sixty-eight thousand, nine hundred twenty-eight".