684181409 has 2 divisors, whose sum is σ = 684181410. Its totient is φ = 684181408.

The previous prime is 684181387. The next prime is 684181411. The reversal of 684181409 is 904181486.

684181409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 552391009 + 131790400 = 23503^2 + 11480^2 .

It is a cyclic number.

It is not a de Polignac number, because 684181409 - 2¹² = 684177313 is a prime.

It is a Sophie Germain prime.

Together with 684181411, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (684181499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342090704 + 342090705.

It is an arithmetic number, because the mean of its divisors is an integer number (342090705).

Almost surely, 2^684181409 is an apocalyptic number.

It is an amenable number.

684181409 is a deficient number, since it is larger than the sum of its proper divisors (1).

684181409 is an equidigital number, since it uses as much as digits as its factorization.

684181409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 55296, while the sum is 41.

The square root of 684181409 is about 26156.8616045580. The cubic root of 684181409 is about 881.1646979184.

The spelling of 684181409 in words is "six hundred eighty-four million, one hundred eighty-one thousand, four hundred nine".