665634689280 has 1152 divisors, whose sum is σ = 2688759360000. Its totient is φ = 154457210880.

The previous prime is 665634689263. The next prime is 665634689287. The reversal of 665634689280 is 82986436566.

665634689280 is a `hidden beast` number, since 6 + 6 + 5 + 6 + 3 + 468 + 92 + 80 = 666.

It is a tau number, because it is divible by the number of its divisors (1152).

It is not an unprimeable number, because it can be changed into a prime (665634689287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1907262546 + ... + 1907262894.

It is an arithmetic number, because the mean of its divisors is an integer number (2333992500).

Almost surely, 2^665634689280 is an apocalyptic number.

665634689280 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 665634689280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1344379680000).

665634689280 is an abundant number, since it is smaller than the sum of its proper divisors (2023124670720).

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

665634689280 is a wasteful number, since it uses less digits than its factorization.

665634689280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592 (or 572 counting only the distinct ones).

The product of its (nonzero) digits is 89579520, while the sum is 63.

The spelling of 665634689280 in words is "six hundred sixty-five billion, six hundred thirty-four million, six hundred eighty-nine thousand, two hundred eighty".