669808649 has 4 divisors (see below), whose sum is σ = 672588180. Its totient is φ = 667029120.

The previous prime is 669808631. The next prime is 669808681. The reversal of 669808649 is 946808966.

669808649 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 621255625 + 48553024 = 24925^2 + 6968^2 .

It is a cyclic number.

It is not a de Polignac number, because 669808649 - 2²⁰ = 668760073 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 669808594 and 669808603.

It is not an unprimeable number, because it can be changed into a prime (669868649) 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, 1389404 + ... + 1389885.

It is an arithmetic number, because the mean of its divisors is an integer number (168147045).

Almost surely, 2^669808649 is an apocalyptic number.

It is an amenable number.

669808649 is a deficient number, since it is larger than the sum of its proper divisors (2779531).

669808649 is a wasteful number, since it uses less digits than its factorization.

669808649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2779530.

The product of its (nonzero) digits is 4478976, while the sum is 56.

The square root of 669808649 is about 25880.6616801039. The cubic root of 669808649 is about 874.9507015491.

The spelling of 669808649 in words is "six hundred sixty-nine million, eight hundred eight thousand, six hundred forty-nine".