1685387657 has 2 divisors, whose sum is σ = 1685387658. Its totient is φ = 1685387656.

The previous prime is 1685387653. The next prime is 1685387699. The reversal of 1685387657 is 7567835861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 952277881 + 733109776 = 30859^2 + 27076^2 .

It is an emirp because it is prime and its reverse (7567835861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1685387657 - 2² = 1685387653 is a prime.

It is not a weakly prime, because it can be changed into another prime (1685387653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842693828 + 842693829.

It is an arithmetic number, because the mean of its divisors is an integer number (842693829).

Almost surely, 2^1685387657 is an apocalyptic number.

It is an amenable number.

1685387657 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685387657 is an equidigital number, since it uses as much as digits as its factorization.

1685387657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8467200, while the sum is 56.

The square root of 1685387657 is about 41053.4731417453. The cubic root of 1685387657 is about 1190.0538207421.

The spelling of 1685387657 in words is "one billion, six hundred eighty-five million, three hundred eighty-seven thousand, six hundred fifty-seven".