688428217 has 2 divisors, whose sum is σ = 688428218. Its totient is φ = 688428216.

The previous prime is 688428211. The next prime is 688428229. The reversal of 688428217 is 712824886.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 495107001 + 193321216 = 22251^2 + 13904^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-688428217 is a prime.

It is not a weakly prime, because it can be changed into another prime (688428211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344214108 + 344214109.

It is an arithmetic number, because the mean of its divisors is an integer number (344214109).

Almost surely, 2^688428217 is an apocalyptic number.

It is an amenable number.

688428217 is a deficient number, since it is larger than the sum of its proper divisors (1).

688428217 is an equidigital number, since it uses as much as digits as its factorization.

688428217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 344064, while the sum is 46.

The square root of 688428217 is about 26237.9156374892. The cubic root of 688428217 is about 882.9841087626.

The spelling of 688428217 in words is "six hundred eighty-eight million, four hundred twenty-eight thousand, two hundred seventeen".