665763840 has 480 divisors, whose sum is σ = 2768156160. Its totient is φ = 148635648.

The previous prime is 665763823. The next prime is 665763851. The reversal of 665763840 is 48367566.

665763840 is a `hidden beast` number, since 6 + 6 + 5 + 7 + 638 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (45).

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 31 ways as a sum of consecutive naturals, for example, 15482859 + ... + 15482901.

It is an arithmetic number, because the mean of its divisors is an integer number (5766992).

Almost surely, 2^665763840 is an apocalyptic number.

665763840 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 665763840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1384078080).

665763840 is an abundant number, since it is smaller than the sum of its proper divisors (2102392320).

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

665763840 is an equidigital number, since it uses as much as digits as its factorization.

665763840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92 (or 60 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 45.

The square root of 665763840 is about 25802.3998883825. The cubic root of 665763840 is about 873.1859407197.

The spelling of 665763840 in words is "six hundred sixty-five million, seven hundred sixty-three thousand, eight hundred forty".