684875509 has 2 divisors, whose sum is σ = 684875510. Its totient is φ = 684875508.

The previous prime is 684875507. The next prime is 684875627. The reversal of 684875509 is 905578486.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 419348484 + 265527025 = 20478^2 + 16295^2 .

It is a cyclic number.

It is not a de Polignac number, because 684875509 - 2¹ = 684875507 is a prime.

Together with 684875507, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (684875507) 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, 342437754 + 342437755.

It is an arithmetic number, because the mean of its divisors is an integer number (342437755).

Almost surely, 2^684875509 is an apocalyptic number.

It is an amenable number.

684875509 is a deficient number, since it is larger than the sum of its proper divisors (1).

684875509 is an equidigital number, since it uses as much as digits as its factorization.

684875509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2419200, while the sum is 52.

The square root of 684875509 is about 26170.1262702342. The cubic root of 684875509 is about 881.4625768618.

The spelling of 684875509 in words is "six hundred eighty-four million, eight hundred seventy-five thousand, five hundred nine".