1605889 has 2 divisors, whose sum is σ = 1605890. Its totient is φ = 1605888.

The previous prime is 1605887. The next prime is 1605907. The reversal of 1605889 is 9885061.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1227664 + 378225 = 1108^2 + 615^2 .

It is an emirp because it is prime and its reverse (9885061) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1605889 - 2¹ = 1605887 is a prime.

Together with 1605887, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1605881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 802944 + 802945.

It is an arithmetic number, because the mean of its divisors is an integer number (802945).

2^1605889 is an apocalyptic number.

It is an amenable number.

1605889 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605889 is an equidigital number, since it uses as much as digits as its factorization.

1605889 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17280, while the sum is 37.

The square root of 1605889 is about 1267.2367576740. The cubic root of 1605889 is about 117.1040300063.

The spelling of 1605889 in words is "one million, six hundred five thousand, eight hundred eighty-nine".