647665665 has 8 divisors (see below), whose sum is σ = 1036265088. Its totient is φ = 345421680.

The previous prime is 647665633. The next prime is 647665693. The reversal of 647665665 is 566566746.

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

It is not a de Polignac number, because 647665665 - 2⁵ = 647665633 is a prime.

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 7 ways as a sum of consecutive naturals, for example, 21588841 + ... + 21588870.

It is an arithmetic number, because the mean of its divisors is an integer number (129533136).

Almost surely, 2^647665665 is an apocalyptic number.

It is an amenable number.

647665665 is a deficient number, since it is larger than the sum of its proper divisors (388599423).

647665665 is a wasteful number, since it uses less digits than its factorization.

647665665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43177719.

The product of its digits is 5443200, while the sum is 51.

The square root of 647665665 is about 25449.2763158405. The cubic root of 647665665 is about 865.2008911156.

The spelling of 647665665 in words is "six hundred forty-seven million, six hundred sixty-five thousand, six hundred sixty-five".