66689666 has 4 divisors (see below), whose sum is σ = 100034502. Its totient is φ = 33344832.

The previous prime is 66689659. The next prime is 66689671. The reversal of 66689666 is 66698666.

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

It can be written as a sum of positive squares in only one way, i.e., 66015625 + 674041 = 8125^2 + 821^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16672415 + ... + 16672418.

Almost surely, 2^66689666 is an apocalyptic number.

66689666 is a deficient number, since it is larger than the sum of its proper divisors (33344836).

66689666 is a wasteful number, since it uses less digits than its factorization.

66689666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33344835.

The product of its digits is 3359232, while the sum is 53.

The square root of 66689666 is about 8166.3741036031. The cubic root of 66689666 is about 405.5267565408.

The spelling of 66689666 in words is "sixty-six million, six hundred eighty-nine thousand, six hundred sixty-six".