66109813 has 16 divisors (see below), whose sum is σ = 82612224. Its totient is φ = 51395760.

The previous prime is 66109801. The next prime is 66109847. The reversal of 66109813 is 31890166.

It is a cyclic number.

It is not a de Polignac number, because 66109813 - 2⁹ = 66109301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66109313) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49156 + ... + 50482.

It is an arithmetic number, because the mean of its divisors is an integer number (5163264).

Almost surely, 2^66109813 is an apocalyptic number.

It is an amenable number.

66109813 is a deficient number, since it is larger than the sum of its proper divisors (16502411).

66109813 is a wasteful number, since it uses less digits than its factorization.

66109813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1992.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 66109813 is about 8130.7941186578. The cubic root of 66109813 is about 404.3480095329.

Adding to 66109813 its reverse (31890166), we get a palindrome (97999979).

The spelling of 66109813 in words is "sixty-six million, one hundred nine thousand, eight hundred thirteen".