665400 has 48 divisors (see below), whose sum is σ = 2064600. Its totient is φ = 177280.

The previous prime is 665387. The next prime is 665419. The reversal of 665400 is 4566.

It is a hoax number, since the sum of its digits (21) coincides with the sum of the digits of its distinct prime factors.

It is a nialpdrome in base 10.

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 665400.

It is an unprimeable number.

665400 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46 + ... + 1154.

2⁶⁶⁵⁴⁰⁰ is an apocalyptic number.

665400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1032300).

665400 is an abundant number, since it is smaller than the sum of its proper divisors (1399200).

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

665400 is a wasteful number, since it uses less digits than its factorization.

665400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1128 (or 1119 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 665400 is about 815.7205403813. The cubic root of 665400 is about 87.3026846335.

Adding to 665400 its reverse (4566), we get a palindrome (669966).

The spelling of 665400 in words is "six hundred sixty-five thousand, four hundred".