665784 has 48 divisors (see below), whose sum is σ = 2062320. Its totient is φ = 190080.

The previous prime is 665783. The next prime is 665789. The reversal of 665784 is 487566.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665783) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 157 + ... + 1164.

It is an arithmetic number, because the mean of its divisors is an integer number (42965).

2⁶⁶⁵⁷⁸⁴ 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 665784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1031160).

665784 is an abundant number, since it is smaller than the sum of its proper divisors (1396536).

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

665784 is a wasteful number, since it uses less digits than its factorization.

665784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1340 (or 1333 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 665784 is about 815.9558811602. The cubic root of 665784 is about 87.3194754281.

The spelling of 665784 in words is "six hundred sixty-five thousand, seven hundred eighty-four".