6656609 has 4 divisors (see below), whose sum is σ = 6680580. Its totient is φ = 6632640.

The previous prime is 6656603. The next prime is 6656621. The reversal of 6656609 is 9066566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9066566 = 2 ⋅4533283.

It can be written as a sum of positive squares in 2 ways, for example, as 1882384 + 4774225 = 1372^2 + 2185^2 .

It is a cyclic number.

It is not a de Polignac number, because 6656609 - 2²⁰ = 5608033 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6656603) 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, 11564 + ... + 12125.

It is an arithmetic number, because the mean of its divisors is an integer number (1670145).

Almost surely, 2^6656609 is an apocalyptic number.

It is an amenable number.

6656609 is a deficient number, since it is larger than the sum of its proper divisors (23971).

6656609 is a wasteful number, since it uses less digits than its factorization.

6656609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23970.

The product of its (nonzero) digits is 58320, while the sum is 38.

The square root of 6656609 is about 2580.0405035580. The cubic root of 6656609 is about 188.1125118732.

It can be divided in two parts, 6656 and 609, that multiplied together give a palindrome (4053504).

The spelling of 6656609 in words is "six million, six hundred fifty-six thousand, six hundred nine".