669816 has 64 divisors (see below), whose sum is σ = 2131200. Its totient is φ = 190944.

The previous prime is 669791. The next prime is 669839. The reversal of 669816 is 618966.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1291 + ... + 1733.

It is an arithmetic number, because the mean of its divisors is an integer number (33300).

2⁶⁶⁹⁸¹⁶ 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 669816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1065600).

669816 is an abundant number, since it is smaller than the sum of its proper divisors (1461384).

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

669816 is a wasteful number, since it uses less digits than its factorization.

669816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 465 (or 455 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 669816 is about 818.4228735806. The cubic root of 669816 is about 87.4953902333.

It can be divided in two parts, 669 and 816, that added together give a triangular number (1485 = T₅₄).

The spelling of 669816 in words is "six hundred sixty-nine thousand, eight hundred sixteen".