668560 has 40 divisors (see below), whose sum is σ = 1591416. Its totient is φ = 261120.

The previous prime is 668543. The next prime is 668567. The reversal of 668560 is 65866.

It can be written as a sum of positive squares in 4 ways, for example, as 2704 + 665856 = 52^2 + 816^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (668567) by changing a digit.

668560 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, 4812 + ... + 4948.

2⁶⁶⁸⁵⁶⁰ 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 668560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (795708).

668560 is an abundant number, since it is smaller than the sum of its proper divisors (922856).

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

668560 is a wasteful number, since it uses less digits than its factorization.

668560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211 (or 205 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 668560 is about 817.6551840477. The cubic root of 668560 is about 87.4406672592.

The spelling of 668560 in words is "six hundred sixty-eight thousand, five hundred sixty".