66513665 has 4 divisors (see below), whose sum is σ = 79816404. Its totient is φ = 53210928.

The previous prime is 66513641. The next prime is 66513703. The reversal of 66513665 is 56631566.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 43970161 + 22543504 = 6631^2 + 4748^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66513665 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6651362 + ... + 6651371.

It is an arithmetic number, because the mean of its divisors is an integer number (19954101).

Almost surely, 2^66513665 is an apocalyptic number.

It is an amenable number.

66513665 is a deficient number, since it is larger than the sum of its proper divisors (13302739).

66513665 is a wasteful number, since it uses less digits than its factorization.

66513665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13302738.

The product of its digits is 97200, while the sum is 38.

The square root of 66513665 is about 8155.5910270194. The cubic root of 66513665 is about 405.1696997521.

The spelling of 66513665 in words is "sixty-six million, five hundred thirteen thousand, six hundred sixty-five".