665813280 has 192 divisors, whose sum is σ = 2337527808. Its totient is φ = 157916160.

The previous prime is 665813249. The next prime is 665813297. The reversal of 665813280 is 82318566.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 246819 + ... + 249501.

It is an arithmetic number, because the mean of its divisors is an integer number (12174624).

Almost surely, 2^665813280 is an apocalyptic number.

665813280 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 665813280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1168763904).

665813280 is an abundant number, since it is smaller than the sum of its proper divisors (1671714528).

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

665813280 is a wasteful number, since it uses less digits than its factorization.

665813280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2759 (or 2751 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 39.

The square root of 665813280 is about 25803.3579210149. The cubic root of 665813280 is about 873.2075546123.

The spelling of 665813280 in words is "six hundred sixty-five million, eight hundred thirteen thousand, two hundred eighty".