680989781 has 2 divisors, whose sum is σ = 680989782. Its totient is φ = 680989780.

The previous prime is 680989763. The next prime is 680989783. The reversal of 680989781 is 187989086.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 678133681 + 2856100 = 26041^2 + 1690^2 .

It is a cyclic number.

It is not a de Polignac number, because 680989781 - 2²² = 676795477 is a prime.

It is a super-2 number, since 2×680989781² = 927494163652855922, which contains 22 as substring.

Together with 680989783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (680989783) 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, 340494890 + 340494891.

It is an arithmetic number, because the mean of its divisors is an integer number (340494891).

Almost surely, 2^680989781 is an apocalyptic number.

It is an amenable number.

680989781 is a deficient number, since it is larger than the sum of its proper divisors (1).

680989781 is an equidigital number, since it uses as much as digits as its factorization.

680989781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1741824, while the sum is 56.

The square root of 680989781 is about 26095.7809041998. The cubic root of 680989781 is about 879.7923843034.

The spelling of 680989781 in words is "six hundred eighty million, nine hundred eighty-nine thousand, seven hundred eighty-one".