1685819521 has 2 divisors, whose sum is σ = 1685819522. Its totient is φ = 1685819520.

The previous prime is 1685819519. The next prime is 1685819537. The reversal of 1685819521 is 1259185861.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1683050625 + 2768896 = 41025^2 + 1664^2 .

It is a cyclic number.

It is not a de Polignac number, because 1685819521 - 2¹ = 1685819519 is a prime.

Together with 1685819519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1685819621) 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, 842909760 + 842909761.

It is an arithmetic number, because the mean of its divisors is an integer number (842909761).

Almost surely, 2^1685819521 is an apocalyptic number.

It is an amenable number.

1685819521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685819521 is an equidigital number, since it uses as much as digits as its factorization.

1685819521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 172800, while the sum is 46.

The square root of 1685819521 is about 41058.7325790751. The cubic root of 1685819521 is about 1190.1554585878.

The spelling of 1685819521 in words is "one billion, six hundred eighty-five million, eight hundred nineteen thousand, five hundred twenty-one".