665728 has 32 divisors (see below), whose sum is σ = 1517760. Its totient is φ = 284928.
The previous prime is 665723. The next prime is 665747. The reversal of 665728 is 827566.
It is a tau number, because it is divible by the number of its divisors (32).
It is a junction number, because it is equal to n+sod(n) for n = 665693 and 665702.
It is not an unprimeable number, because it can be changed into a prime (665723) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 525 + ... + 1267.
It is an arithmetic number, because the mean of its divisors is an integer number (47430).
2665728 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 665728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (758880).
665728 is an abundant number, since it is smaller than the sum of its proper divisors (852032).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
665728 is an equidigital number, since it uses as much as digits as its factorization.
665728 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 764 (or 752 counting only the distinct ones).
The product of its digits is 20160, while the sum is 34.
The square root of 665728 is about 815.9215648578. The cubic root of 665728 is about 87.3170271727.
The spelling of 665728 in words is "six hundred sixty-five thousand, seven hundred twenty-eight".
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