665889280 has 80 divisors (see below), whose sum is σ = 1824704640. Its totient is φ = 228298752.

The previous prime is 665889277. The next prime is 665889299. The reversal of 665889280 is 82988566.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 660 + ... + 36499.

It is an arithmetic number, because the mean of its divisors is an integer number (22808808).

Almost surely, 2^665889280 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 665889280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (912352320).

665889280 is an abundant number, since it is smaller than the sum of its proper divisors (1158815360).

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

665889280 is an equidigital number, since it uses as much as digits as its factorization.

665889280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37189 (or 37173 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 52.

The square root of 665889280 is about 25804.8305555375. The cubic root of 665889280 is about 873.2407777652.

The spelling of 665889280 in words is "six hundred sixty-five million, eight hundred eighty-nine thousand, two hundred eighty".