66616791 has 4 divisors (see below), whose sum is σ = 88822392. Its totient is φ = 44411192.

The previous prime is 66616721. The next prime is 66616843. The reversal of 66616791 is 19761666.

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

It is a cyclic number.

It is not a de Polignac number, because 66616791 - 2⁷ = 66616663 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66616721) 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 3 ways as a sum of consecutive naturals, for example, 11102796 + ... + 11102801.

It is an arithmetic number, because the mean of its divisors is an integer number (22205598).

Almost surely, 2^66616791 is an apocalyptic number.

66616791 is a deficient number, since it is larger than the sum of its proper divisors (22205601).

66616791 is a wasteful number, since it uses less digits than its factorization.

66616791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22205600.

The product of its digits is 81648, while the sum is 42.

The square root of 66616791 is about 8161.9109894681. The cubic root of 66616791 is about 405.3789898513.

The spelling of 66616791 in words is "sixty-six million, six hundred sixteen thousand, seven hundred ninety-one".