665408 has 28 divisors (see below), whose sum is σ = 1360932. Its totient is φ = 322560.

The previous prime is 665387. The next prime is 665419. The reversal of 665408 is 804566.

It can be written as a sum of positive squares in 2 ways, for example, as 529984 + 135424 = 728^2 + 368^2 .

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 665408.

It is an unprimeable number.

665408 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 3 ways as a sum of consecutive naturals, for example, 2228 + ... + 2508.

2⁶⁶⁵⁴⁰⁸ 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 665408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (680466).

665408 is an abundant number, since it is smaller than the sum of its proper divisors (695524).

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

665408 is a wasteful number, since it uses less digits than its factorization.

665408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330 (or 320 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 665408 is about 815.7254440067. The cubic root of 665408 is about 87.3030345076.

The spelling of 665408 in words is "six hundred sixty-five thousand, four hundred eight".