688343861 has 2 divisors, whose sum is σ = 688343862. Its totient is φ = 688343860.

The previous prime is 688343849. The next prime is 688343867. The reversal of 688343861 is 168343886.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 649281361 + 39062500 = 25481^2 + 6250^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-688343861 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688343867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344171930 + 344171931.

It is an arithmetic number, because the mean of its divisors is an integer number (344171931).

Almost surely, 2^688343861 is an apocalyptic number.

It is an amenable number.

688343861 is a deficient number, since it is larger than the sum of its proper divisors (1).

688343861 is an equidigital number, since it uses as much as digits as its factorization.

688343861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 663552, while the sum is 47.

The square root of 688343861 is about 26236.3080672567. The cubic root of 688343861 is about 882.9480420393.

The spelling of 688343861 in words is "six hundred eighty-eight million, three hundred forty-three thousand, eight hundred sixty-one".