669984 has 48 divisors (see below), whose sum is σ = 2011968. Its totient is φ = 191232.

The previous prime is 669971. The next prime is 669989. The reversal of 669984 is 489966.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a d-powerful number, because it can be written as 6 + 6⁶ + 9⁵ + 9⁶ + 8⁵ + 4³ .

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 669984.

It is not an unprimeable number, because it can be changed into a prime (669989) by changing a digit.

669984 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 7 ways as a sum of consecutive naturals, for example, 174 + ... + 1170.

It is an arithmetic number, because the mean of its divisors is an integer number (41916).

2⁶⁶⁹⁹⁸⁴ 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 669984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1005984).

669984 is an abundant number, since it is smaller than the sum of its proper divisors (1341984).

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

669984 is a wasteful number, since it uses less digits than its factorization.

669984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1017 (or 1009 counting only the distinct ones).

The product of its digits is 93312, while the sum is 42.

The square root of 669984 is about 818.5255035733. The cubic root of 669984 is about 87.5027046783.

It can be divided in two parts, 669 and 984, that added together give a triangular number (1653 = T₅₇).

The spelling of 669984 in words is "six hundred sixty-nine thousand, nine hundred eighty-four".