66649691 has 8 divisors (see below), whose sum is σ = 68746560. Its totient is φ = 64568448.

The previous prime is 66649679. The next prime is 66649711. The reversal of 66649691 is 19694666.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66649691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66649621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5075 + ... + 12611.

It is an arithmetic number, because the mean of its divisors is an integer number (8593320).

Almost surely, 2^66649691 is an apocalyptic number.

66649691 is a deficient number, since it is larger than the sum of its proper divisors (2096869).

66649691 is a wasteful number, since it uses less digits than its factorization.

66649691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7813.

The product of its digits is 419904, while the sum is 47.

The square root of 66649691 is about 8163.9262000584. The cubic root of 66649691 is about 405.4457136387.

The spelling of 66649691 in words is "sixty-six million, six hundred forty-nine thousand, six hundred ninety-one".