669978 has 32 divisors (see below), whose sum is σ = 1569600. Its totient is φ = 211248.

The previous prime is 669971. The next prime is 669989. The reversal of 669978 is 879966.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 669978.

It is not an unprimeable number, because it can be changed into a prime (669971) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 700 + ... + 1352.

It is an arithmetic number, because the mean of its divisors is an integer number (49050).

2⁶⁶⁹⁹⁷⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 669978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (784800).

669978 is an abundant number, since it is smaller than the sum of its proper divisors (899622).

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

669978 is a wasteful number, since it uses less digits than its factorization.

669978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 683 (or 677 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 669978 is about 818.5218384380. The cubic root of 669978 is about 87.5024434692.

The spelling of 669978 in words is "six hundred sixty-nine thousand, nine hundred seventy-eight".