1685625509 has 2 divisors, whose sum is σ = 1685625510. Its totient is φ = 1685625508.

The previous prime is 1685625443. The next prime is 1685625563. The reversal of 1685625509 is 9055265861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1676493025 + 9132484 = 40945^2 + 3022^2 .

It is a cyclic number.

It is not a de Polignac number, because 1685625509 - 2¹⁶ = 1685559973 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1685625569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842812754 + 842812755.

It is an arithmetic number, because the mean of its divisors is an integer number (842812755).

Almost surely, 2^1685625509 is an apocalyptic number.

It is an amenable number.

1685625509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685625509 is an equidigital number, since it uses as much as digits as its factorization.

1685625509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648000, while the sum is 47.

The square root of 1685625509 is about 41056.3698955473. The cubic root of 1685625509 is about 1190.1098006163.

The spelling of 1685625509 in words is "one billion, six hundred eighty-five million, six hundred twenty-five thousand, five hundred nine".