684650861 has 2 divisors, whose sum is σ = 684650862. Its totient is φ = 684650860.

The previous prime is 684650839. The next prime is 684650881. The reversal of 684650861 is 168056486.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 585349636 + 99301225 = 24194^2 + 9965^2 .

It is a cyclic number.

It is not a de Polignac number, because 684650861 - 2⁶ = 684650797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (684650881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342325430 + 342325431.

It is an arithmetic number, because the mean of its divisors is an integer number (342325431).

Almost surely, 2^684650861 is an apocalyptic number.

It is an amenable number.

684650861 is a deficient number, since it is larger than the sum of its proper divisors (1).

684650861 is an equidigital number, since it uses as much as digits as its factorization.

684650861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 276480, while the sum is 44.

The square root of 684650861 is about 26165.8338487425. The cubic root of 684650861 is about 881.3661892910.

The spelling of 684650861 in words is "six hundred eighty-four million, six hundred fifty thousand, eight hundred sixty-one".