1664605 has 4 divisors (see below), whose sum is σ = 1997532. Its totient is φ = 1331680.

The previous prime is 1664569. The next prime is 1664627. The reversal of 1664605 is 5064661.

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 962361 + 702244 = 981^2 + 838^2 .

It is not a de Polignac number, because 1664605 - 2¹⁵ = 1631837 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166456 + ... + 166465.

It is an arithmetic number, because the mean of its divisors is an integer number (499383).

2^1664605 is an apocalyptic number.

It is an amenable number.

1664605 is a deficient number, since it is larger than the sum of its proper divisors (332927).

1664605 is an equidigital number, since it uses as much as digits as its factorization.

1664605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332926.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 1664605 is about 1290.1957215865. The cubic root of 1664605 is about 118.5142024554.

The spelling of 1664605 in words is "one million, six hundred sixty-four thousand, six hundred five".