665648865 has 96 divisors (see below), whose sum is σ = 1394565120. Its totient is φ = 287134848.

The previous prime is 665648849. The next prime is 665648873. The reversal of 665648865 is 568846566.

It is a happy number.

It is not a de Polignac number, because 665648865 - 2⁴ = 665648849 is a prime.

It is a super-2 number, since 2×665648865² = 886176822951576450, which contains 22 as substring.

Its product of digits (8294400) is a multiple of the sum of its prime divisors (1280).

It is a Curzon number.

It is an unprimeable number.

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 95 ways as a sum of consecutive naturals, for example, 571774 + ... + 572936.

It is an arithmetic number, because the mean of its divisors is an integer number (14526720).

Almost surely, 2^665648865 is an apocalyptic number.

It is an amenable number.

665648865 is an abundant number, since it is smaller than the sum of its proper divisors (728916255).

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

665648865 is a wasteful number, since it uses less digits than its factorization.

665648865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1283 (or 1280 counting only the distinct ones).

The product of its digits is 8294400, while the sum is 54.

The square root of 665648865 is about 25800.1718017536. The cubic root of 665648865 is about 873.1356724778.

The spelling of 665648865 in words is "six hundred sixty-five million, six hundred forty-eight thousand, eight hundred sixty-five".