1605985897 has 2 divisors, whose sum is σ = 1605985898. Its totient is φ = 1605985896.

The previous prime is 1605985889. The next prime is 1605985981. The reversal of 1605985897 is 7985895061.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1566497241 + 39488656 = 39579^2 + 6284^2 .

It is a cyclic number.

It is not a de Polignac number, because 1605985897 - 2³ = 1605985889 is a prime.

It is not a weakly prime, because it can be changed into another prime (1605985397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 802992948 + 802992949.

It is an arithmetic number, because the mean of its divisors is an integer number (802992949).

Almost surely, 2^1605985897 is an apocalyptic number.

It is an amenable number.

1605985897 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605985897 is an equidigital number, since it uses as much as digits as its factorization.

1605985897 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5443200, while the sum is 58.

The square root of 1605985897 is about 40074.7538607538. The cubic root of 1605985897 is about 1171.0638525435.

The spelling of 1605985897 in words is "one billion, six hundred five million, nine hundred eighty-five thousand, eight hundred ninety-seven".