1640605 has 4 divisors (see below), whose sum is σ = 1968732. Its totient is φ = 1312480.

The previous prime is 1640599. The next prime is 1640609. The reversal of 1640605 is 5060461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 338724 + 1301881 = 582^2 + 1141^2 .

It is not a de Polignac number, because 1640605 - 2¹⁷ = 1509533 is a prime.

It is a super-3 number, since 3×1640605³ = 13247482275193335375, which contains 333 as substring.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640609) 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, 164056 + ... + 164065.

It is an arithmetic number, because the mean of its divisors is an integer number (492183).

2^1640605 is an apocalyptic number.

It is an amenable number.

1640605 is a deficient number, since it is larger than the sum of its proper divisors (328127).

1640605 is an equidigital number, since it uses as much as digits as its factorization.

1640605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328126.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 1640605 is about 1280.8610385206. The cubic root of 1640605 is about 117.9418702482.

The spelling of 1640605 in words is "one million, six hundred forty thousand, six hundred five".