1684645009 has 2 divisors, whose sum is σ = 1684645010. Its totient is φ = 1684645008.

The previous prime is 1684645007. The next prime is 1684645037. The reversal of 1684645009 is 9005464861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1090650625 + 593994384 = 33025^2 + 24372^2 .

It is a cyclic number.

It is not a de Polignac number, because 1684645009 - 2¹ = 1684645007 is a prime.

It is a super-2 number, since 2×1684645009² = 5676057612697220162, which contains 22 as substring.

Together with 1684645007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1684645007) 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, 842322504 + 842322505.

It is an arithmetic number, because the mean of its divisors is an integer number (842322505).

Almost surely, 2^1684645009 is an apocalyptic number.

It is an amenable number.

1684645009 is a deficient number, since it is larger than the sum of its proper divisors (1).

1684645009 is an equidigital number, since it uses as much as digits as its factorization.

1684645009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 207360, while the sum is 43.

The square root of 1684645009 is about 41044.4272587644. The cubic root of 1684645009 is about 1189.8790002433.

The spelling of 1684645009 in words is "one billion, six hundred eighty-four million, six hundred forty-five thousand, nine".