688657 has 2 divisors, whose sum is σ = 688658. Its totient is φ = 688656.

The previous prime is 688637. The next prime is 688661. The reversal of 688657 is 756886.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 665856 + 22801 = 816^2 + 151^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-688657 is a prime.

It is a Chen prime.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (688627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344328 + 344329.

It is an arithmetic number, because the mean of its divisors is an integer number (344329).

2⁶⁸⁸⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

688657 is a deficient number, since it is larger than the sum of its proper divisors (1).

688657 is an equidigital number, since it uses as much as digits as its factorization.

688657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 40.

The square root of 688657 is about 829.8536015467. The cubic root of 688657 is about 88.3081910961.

The spelling of 688657 in words is "six hundred eighty-eight thousand, six hundred fifty-seven".