6645409 has 4 divisors (see below), whose sum is σ = 6736516. Its totient is φ = 6554304.

The previous prime is 6645391. The next prime is 6645461. The reversal of 6645409 is 9045466.

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 4528384 + 2117025 = 2128^2 + 1455^2 .

It is a cyclic number.

It is not a de Polignac number, because 6645409 - 2¹¹ = 6643361 is a prime.

It is a super-2 number, since 2×6645409² = 88322921554562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6645469) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45444 + ... + 45589.

It is an arithmetic number, because the mean of its divisors is an integer number (1684129).

Almost surely, 2^6645409 is an apocalyptic number.

It is an amenable number.

6645409 is a deficient number, since it is larger than the sum of its proper divisors (91107).

6645409 is an equidigital number, since it uses as much as digits as its factorization.

6645409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91106.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 6645409 is about 2577.8690812374. The cubic root of 6645409 is about 188.0069504749.

The spelling of 6645409 in words is "six million, six hundred forty-five thousand, four hundred nine".