3645209 has 4 divisors (see below), whose sum is σ = 3650916. Its totient is φ = 3639504.

The previous prime is 3645193. The next prime is 3645227. The reversal of 3645209 is 9025463.

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 3115225 + 529984 = 1765^2 + 728^2 .

It is a cyclic number.

It is not a de Polignac number, because 3645209 - 2⁴ = 3645193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3645289) 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, 1754 + ... + 3219.

It is an arithmetic number, because the mean of its divisors is an integer number (912729).

Almost surely, 2^3645209 is an apocalyptic number.

It is an amenable number.

3645209 is a deficient number, since it is larger than the sum of its proper divisors (5707).

3645209 is an equidigital number, since it uses as much as digits as its factorization.

3645209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5706.

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 3645209 is about 1909.2430437218. The cubic root of 3645209 is about 153.9007765848.

The spelling of 3645209 in words is "three million, six hundred forty-five thousand, two hundred nine".