684727991 has 2 divisors, whose sum is σ = 684727992. Its totient is φ = 684727990.

The previous prime is 684727987. The next prime is 684728017. The reversal of 684727991 is 199727486.

684727991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 684727991 - 2² = 684727987 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 (684727891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342363995 + 342363996.

It is an arithmetic number, because the mean of its divisors is an integer number (342363996).

Almost surely, 2^684727991 is an apocalyptic number.

684727991 is a deficient number, since it is larger than the sum of its proper divisors (1).

684727991 is an equidigital number, since it uses as much as digits as its factorization.

684727991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1524096, while the sum is 53.

The square root of 684727991 is about 26167.3076758004. The cubic root of 684727991 is about 881.3992850996.

The spelling of 684727991 in words is "six hundred eighty-four million, seven hundred twenty-seven thousand, nine hundred ninety-one".