66108813 has 4 divisors (see below), whose sum is σ = 88145088. Its totient is φ = 44072540.

The previous prime is 66108803. The next prime is 66108821. The reversal of 66108813 is 31880166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66108813 - 2⁴ = 66108797 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66108803) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11018133 + ... + 11018138.

It is an arithmetic number, because the mean of its divisors is an integer number (22036272).

Almost surely, 2^66108813 is an apocalyptic number.

It is an amenable number.

66108813 is a deficient number, since it is larger than the sum of its proper divisors (22036275).

66108813 is a wasteful number, since it uses less digits than its factorization.

66108813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22036274.

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 66108813 is about 8130.7326238169. The cubic root of 66108813 is about 404.3459707531.

Adding to 66108813 its reverse (31880166), we get a palindrome (97988979).

The spelling of 66108813 in words is "sixty-six million, one hundred eight thousand, eight hundred thirteen".