665712 has 80 divisors (see below), whose sum is σ = 2023680. Its totient is φ = 209088.

The previous prime is 665677. The next prime is 665713. The reversal of 665712 is 217566.

665712 = 159² + 160² + ... + 181².

665712 is a `hidden beast` number, since 6 + 657 + 1 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665713) by changing a digit.

665712 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 15 ways as a sum of consecutive naturals, for example, 9903 + ... + 9969.

It is an arithmetic number, because the mean of its divisors is an integer number (25296).

2⁶⁶⁵⁷¹² 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 665712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1011840).

665712 is an abundant number, since it is smaller than the sum of its proper divisors (1357968).

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

665712 is a wasteful number, since it uses less digits than its factorization.

665712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107 (or 95 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 665712 is about 815.9117599349. The cubic root of 665712 is about 87.3163276460.

It can be divided in two parts, 66 and 5712, that added together give a triangular number (5778 = T₁₀₇).

The spelling of 665712 in words is "six hundred sixty-five thousand, seven hundred twelve".