669818656 has 72 divisors (see below), whose sum is σ = 1437159024. Its totient is φ = 307157760.

The previous prime is 669818641. The next prime is 669818663. The reversal of 669818656 is 656818966.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 669818597 and 669818606.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1140795 + ... + 1141381.

It is an arithmetic number, because the mean of its divisors is an integer number (19960542).

Almost surely, 2^669818656 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 669818656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (718579512).

669818656 is an abundant number, since it is smaller than the sum of its proper divisors (767340368).

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

669818656 is a wasteful number, since it uses less digits than its factorization.

669818656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 834 (or 813 counting only the distinct ones).

The product of its digits is 3732480, while the sum is 55.

The square root of 669818656 is about 25880.8550090603. The cubic root of 669818656 is about 874.9550588074.

The spelling of 669818656 in words is "six hundred sixty-nine million, eight hundred eighteen thousand, six hundred fifty-six".