660640 has 24 divisors (see below), whose sum is σ = 1561140. Its totient is φ = 264192.

The previous prime is 660619. The next prime is 660643. The reversal of 660640 is 46066.

It can be written as a sum of positive squares in 2 ways, for example, as 659344 + 1296 = 812^2 + 36^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660643) by changing a digit.

660640 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 3 ways as a sum of consecutive naturals, for example, 1905 + ... + 2224.

2⁶⁶⁰⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

660640 is an abundant number, since it is smaller than the sum of its proper divisors (900500).

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

660640 is a wasteful number, since it uses less digits than its factorization.

660640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4144 (or 4136 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 660640 is about 812.7976377918. The cubic root of 660640 is about 87.0940103257.

The spelling of 660640 in words is "six hundred sixty thousand, six hundred forty".