665617280800 has 144 divisors (see below), whose sum is σ = 1655627783040. Its totient is φ = 261259914240.

The previous prime is 665617280789. The next prime is 665617280819. The reversal of 665617280800 is 8082716566.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10269294 + ... + 10333906.

It is an arithmetic number, because the mean of its divisors is an integer number (11497415160).

Almost surely, 2^665617280800 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 665617280800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (827813891520).

665617280800 is an abundant number, since it is smaller than the sum of its proper divisors (990010502240).

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

665617280800 is a wasteful number, since it uses less digits than its factorization.

665617280800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64875 (or 64862 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 49.

The spelling of 665617280800 in words is "six hundred sixty-five billion, six hundred seventeen million, two hundred eighty thousand, eight hundred".