669509 has 4 divisors (see below), whose sum is σ = 672204. Its totient is φ = 666816.

The previous prime is 669481. The next prime is 669527. The reversal of 669509 is 905966.

669509 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, and also an emirpimes, since its reverse is a distinct semiprime: 905966 = 2 ⋅452983.

It can be written as a sum of positive squares in 2 ways, for example, as 422500 + 247009 = 650^2 + 497^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-669509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660509) 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, 932 + ... + 1485.

It is an arithmetic number, because the mean of its divisors is an integer number (168051).

2⁶⁶⁹⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

669509 is a deficient number, since it is larger than the sum of its proper divisors (2695).

669509 is a wasteful number, since it uses less digits than its factorization.

669509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2694.

The product of its (nonzero) digits is 14580, while the sum is 35.

The square root of 669509 is about 818.2352962321. The cubic root of 669509 is about 87.4820207957.

The spelling of 669509 in words is "six hundred sixty-nine thousand, five hundred nine".