1609 has 2 divisors, whose sum is σ = 1610.
Its totient is φ = 1608.
The previous prime is 1607. The next prime is 1613. The reversal of 1609 is 9061.
It can be divided in two parts, 160 and 9, that added together give a square (169 = 132).
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 1600 + 9 = 40^2 + 3^2
It is a cyclic number.
It is not a de Polignac number, because 1609 - 21 = 1607 is a prime.
Together with 1607, it forms a pair of twin primes.
It is a plaindrome in base 7 and base 11.
It is a nialpdrome in base 8 and base 12.
It is a junction number, because it is equal to n+sod(n) for n = 1592 and 1601.
It is not a weakly prime, because it can be changed into another prime (1601) 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, 804 + 805.
It is an arithmetic number, because the mean of its divisors is an integer number (805).
It is an amenable number.
1609 is a deficient number, since it is larger than the sum of its proper divisors (1).
1609 is an equidigital number, since it uses as much as digits as its factorization.
1609 is an odious number, because the sum of its binary digits is odd.
The product of its (nonzero) digits is 54, while the sum is 16.
The square root of 1609 is about 40.1123422403.
The cubic root of 1609 is about 11.7179600949.
The spelling of 1609 in words is "one thousand, six hundred nine".