665940 has 48 divisors (see below), whose sum is σ = 2036160. Its totient is φ = 161280.

The previous prime is 665923. The next prime is 665947. The reversal of 665940 is 49566.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 665898 and 665907.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665947) by changing a digit.

665940 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 15 ways as a sum of consecutive naturals, for example, 156 + ... + 1164.

It is an arithmetic number, because the mean of its divisors is an integer number (42420).

2⁶⁶⁵⁹⁴⁰ is an apocalyptic number.

665940 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 665940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1018080).

665940 is an abundant number, since it is smaller than the sum of its proper divisors (1370220).

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

665940 is a wasteful number, since it uses less digits than its factorization.

665940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1032 (or 1030 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 30.

The square root of 665940 is about 816.0514689650. The cubic root of 665940 is about 87.3262948442.

It can be divided in two parts, 66 and 5940, that added together give a palindrome (6006).

The spelling of 665940 in words is "six hundred sixty-five thousand, nine hundred forty".