668440 has 32 divisors (see below), whose sum is σ = 1594080. Its totient is φ = 251392.

The previous prime is 668417. The next prime is 668471. The reversal of 668440 is 44866.

It is a junction number, because it is equal to n+sod(n) for n = 668399 and 668408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 189 + ... + 1171.

It is an arithmetic number, because the mean of its divisors is an integer number (49815).

2⁶⁶⁸⁴⁴⁰ 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 668440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (797040).

668440 is an abundant number, since it is smaller than the sum of its proper divisors (925640).

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

668440 is a wasteful number, since it uses less digits than its factorization.

668440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1011 (or 1007 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 668440 is about 817.5818001888. The cubic root of 668440 is about 87.4354353639.

It can be divided in two parts, 6684 and 40, that added together give a square (6724 = 82²).

The spelling of 668440 in words is "six hundred sixty-eight thousand, four hundred forty".