665718768 has 180 divisors, whose sum is σ = 2206134840. Its totient is φ = 186151680.

The previous prime is 665718749. The next prime is 665718829. The reversal of 665718768 is 867817566.

665718768 is a `hidden beast` number, since 6 + 6 + 571 + 8 + 7 + 68 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 225043 + ... + 227981.

Almost surely, 2^665718768 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 665718768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1103067420).

665718768 is an abundant number, since it is smaller than the sum of its proper divisors (1540416072).

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

665718768 is a wasteful number, since it uses less digits than its factorization.

665718768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2988 (or 2968 counting only the distinct ones).

The product of its digits is 3386880, while the sum is 54.

The square root of 665718768 is about 25801.5264664709. The cubic root of 665718768 is about 873.1662354717.

It can be divided in two parts, 6657 and 18768, that added together give a triangular number (25425 = T₂₂₅).

The spelling of 665718768 in words is "six hundred sixty-five million, seven hundred eighteen thousand, seven hundred sixty-eight".