1664645 has 6 divisors (see below), whose sum is σ = 2001042. Its totient is φ = 1329408.

The previous prime is 1664633. The next prime is 1664651. The reversal of 1664645 is 5464661.

It can be written as a sum of positive squares in 3 ways, for example, as 1214404 + 450241 = 1102^2 + 671^2 .

It is not a de Polignac number, because 1664645 - 2¹⁴ = 1648261 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 5 ways as a sum of consecutive naturals, for example, 2597 + ... + 3173.

It is an arithmetic number, because the mean of its divisors is an integer number (333507).

2^1664645 is an apocalyptic number.

It is an amenable number.

1664645 is a deficient number, since it is larger than the sum of its proper divisors (336397).

1664645 is an frugal number, since it uses more digits than its factorization.

1664645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1159 (or 582 counting only the distinct ones).

The product of its digits is 17280, while the sum is 32.

The square root of 1664645 is about 1290.2112230174. The cubic root of 1664645 is about 118.5151517357.

The spelling of 1664645 in words is "one million, six hundred sixty-four thousand, six hundred forty-five".