680871649 has 2 divisors, whose sum is σ = 680871650. Its totient is φ = 680871648.

The previous prime is 680871647. The next prime is 680871671. The reversal of 680871649 is 946178086.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 678967249 + 1904400 = 26057^2 + 1380^2 .

It is a cyclic number.

It is not a de Polignac number, because 680871649 - 2¹ = 680871647 is a prime.

Together with 680871647, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (680871647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340435824 + 340435825.

It is an arithmetic number, because the mean of its divisors is an integer number (340435825).

Almost surely, 2^680871649 is an apocalyptic number.

It is an amenable number.

680871649 is a deficient number, since it is larger than the sum of its proper divisors (1).

680871649 is an equidigital number, since it uses as much as digits as its factorization.

680871649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 580608, while the sum is 49.

The square root of 680871649 is about 26093.5173750110. The cubic root of 680871649 is about 879.7415085306.

The spelling of 680871649 in words is "six hundred eighty million, eight hundred seventy-one thousand, six hundred forty-nine".