1605997 has 4 divisors (see below), whose sum is σ = 1610140. Its totient is φ = 1601856.

The previous prime is 1605979. The next prime is 1606009. The reversal of 1605997 is 7995061.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7995061 = 131 ⋅61031.

It can be written as a sum of positive squares in 2 ways, for example, as 292681 + 1313316 = 541^2 + 1146^2 .

It is a cyclic number.

It is not a de Polignac number, because 1605997 - 2⁷ = 1605869 is a prime.

It is a Duffinian number.

1605997 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1605907) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1422 + ... + 2287.

It is an arithmetic number, because the mean of its divisors is an integer number (402535).

2^1605997 is an apocalyptic number.

It is an amenable number.

1605997 is a deficient number, since it is larger than the sum of its proper divisors (4143).

1605997 is an equidigital number, since it uses as much as digits as its factorization.

1605997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4142.

The product of its (nonzero) digits is 17010, while the sum is 37.

The square root of 1605997 is about 1267.2793693578. The cubic root of 1605997 is about 117.1066551258.

The spelling of 1605997 in words is "one million, six hundred five thousand, nine hundred ninety-seven".