66616091 has 4 divisors (see below), whose sum is σ = 66657000. Its totient is φ = 66575184.

The previous prime is 66616057. The next prime is 66616097. The reversal of 66616091 is 19061666.

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 66616091 - 2¹⁰ = 66615067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66616097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17906 + ... + 21303.

It is an arithmetic number, because the mean of its divisors is an integer number (16664250).

Almost surely, 2^66616091 is an apocalyptic number.

66616091 is a deficient number, since it is larger than the sum of its proper divisors (40909).

66616091 is a wasteful number, since it uses less digits than its factorization.

66616091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40908.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 66616091 is about 8161.8681072411. The cubic root of 66616091 is about 405.3775699576.

The spelling of 66616091 in words is "sixty-six million, six hundred sixteen thousand, ninety-one".