669856 has 36 divisors (see below), whose sum is σ = 1457946. Its totient is φ = 302720.

The previous prime is 669853. The next prime is 669857. The reversal of 669856 is 658966.

It can be written as a sum of positive squares in only one way, i.e., 435600 + 234256 = 660^2 + 484^2 .

It is not an unprimeable number, because it can be changed into a prime (669853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3786 + ... + 3958.

2⁶⁶⁹⁸⁵⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 669856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (728973).

669856 is an abundant number, since it is smaller than the sum of its proper divisors (788090).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

669856 is a wasteful number, since it uses less digits than its factorization.

669856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205 (or 186 counting only the distinct ones).

The product of its digits is 77760, while the sum is 40.

The square root of 669856 is about 818.4473104605. The cubic root of 669856 is about 87.4971318788.

The spelling of 669856 in words is "six hundred sixty-nine thousand, eight hundred fifty-six".