665839680 has 224 divisors, whose sum is σ = 2442545280. Its totient is φ = 151879680.

The previous prime is 665839651. The next prime is 665839687. The reversal of 665839680 is 86938566.

665839680 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is not an unprimeable number, because it can be changed into a prime (665839687) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 177666 + ... + 181374.

It is an arithmetic number, because the mean of its divisors is an integer number (10904220).

Almost surely, 2^665839680 is an apocalyptic number.

665839680 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 665839680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1221272640).

665839680 is an abundant number, since it is smaller than the sum of its proper divisors (1776705600).

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

665839680 is a wasteful number, since it uses less digits than its factorization.

665839680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3757 (or 3747 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 51.

The square root of 665839680 is about 25803.8694772703. The cubic root of 665839680 is about 873.2190955730.

The spelling of 665839680 in words is "six hundred sixty-five million, eight hundred thirty-nine thousand, six hundred eighty".