665868815 has 8 divisors (see below), whose sum is σ = 799212960. Its totient is φ = 532581472.

The previous prime is 665868799. The next prime is 665868817. The reversal of 665868815 is 518868566.

665868815 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 665868815 - 2⁴ = 665868799 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665868817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18401 + ... + 40869.

It is an arithmetic number, because the mean of its divisors is an integer number (99901620).

Almost surely, 2^665868815 is an apocalyptic number.

665868815 is a deficient number, since it is larger than the sum of its proper divisors (133344145).

665868815 is a wasteful number, since it uses less digits than its factorization.

665868815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28401.

The product of its digits is 2764800, while the sum is 53.

The square root of 665868815 is about 25804.4340182070. The cubic root of 665868815 is about 873.2318318057.

The spelling of 665868815 in words is "six hundred sixty-five million, eight hundred sixty-eight thousand, eight hundred fifteen".