657680 has 20 divisors (see below), whose sum is σ = 1529292. Its totient is φ = 263040.

The previous prime is 657661. The next prime is 657703. The reversal of 657680 is 86756.

It can be written as a sum of positive squares in 2 ways, for example, as 456976 + 200704 = 676^2 + 448^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is an unprimeable number.

657680 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4031 + ... + 4190.

2⁶⁵⁷⁶⁸⁰ is an apocalyptic number.

It is an amenable number.

657680 is an abundant number, since it is smaller than the sum of its proper divisors (871612).

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

657680 is a wasteful number, since it uses less digits than its factorization.

657680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8234 (or 8228 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 657680 is about 810.9747221708. The cubic root of 657680 is about 86.9637405601.

The spelling of 657680 in words is "six hundred fifty-seven thousand, six hundred eighty".