64668665 has 4 divisors (see below), whose sum is σ = 77602404. Its totient is φ = 51734928.

The previous prime is 64668649. The next prime is 64668677. The reversal of 64668665 is 56686646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56686646 = 2 ⋅28343323.

It can be written as a sum of positive squares in 2 ways, for example, as 19254544 + 45414121 = 4388^2 + 6739^2 .

It is a cyclic number.

It is not a de Polignac number, because 64668665 - 2⁴ = 64668649 is a prime.

It is a Duffinian 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 3 ways as a sum of consecutive naturals, for example, 6466862 + ... + 6466871.

It is an arithmetic number, because the mean of its divisors is an integer number (19400601).

Almost surely, 2^64668665 is an apocalyptic number.

It is an amenable number.

64668665 is a deficient number, since it is larger than the sum of its proper divisors (12933739).

64668665 is a wasteful number, since it uses less digits than its factorization.

64668665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12933738.

The product of its digits is 1244160, while the sum is 47.

The square root of 64668665 is about 8041.6829706225. The cubic root of 64668665 is about 401.3882285633.

The spelling of 64668665 in words is "sixty-four million, six hundred sixty-eight thousand, six hundred sixty-five".