66991208 has 16 divisors (see below), whose sum is σ = 125768580. Its totient is φ = 33452928.

The previous prime is 66991193. The next prime is 66991231. The reversal of 66991208 is 80219966.

It can be written as a sum of positive squares in 2 ways, for example, as 66552964 + 438244 = 8158^2 + 662^2 .

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, 1916 + ... + 11732.

Almost surely, 2^66991208 is an apocalyptic number.

It is an amenable number.

66991208 is a deficient number, since it is larger than the sum of its proper divisors (58777372).

66991208 is a wasteful number, since it uses less digits than its factorization.

66991208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10676 (or 10672 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 66991208 is about 8184.8156973752. The cubic root of 66991208 is about 406.1370435306.

The spelling of 66991208 in words is "sixty-six million, nine hundred ninety-one thousand, two hundred eight".