66813161 has 4 divisors (see below), whose sum is σ = 66829524. Its totient is φ = 66796800.

The previous prime is 66813151. The next prime is 66813169. The reversal of 66813161 is 16131866.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 27825625 + 38987536 = 5275^2 + 6244^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66813161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66813169) 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, 3581 + ... + 12101.

It is an arithmetic number, because the mean of its divisors is an integer number (16707381).

Almost surely, 2^66813161 is an apocalyptic number.

It is an amenable number.

66813161 is a deficient number, since it is larger than the sum of its proper divisors (16363).

66813161 is an equidigital number, since it uses as much as digits as its factorization.

66813161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16362.

The product of its digits is 5184, while the sum is 32.

The square root of 66813161 is about 8173.9317956538. The cubic root of 66813161 is about 405.7769184662.

The spelling of 66813161 in words is "sixty-six million, eight hundred thirteen thousand, one hundred sixty-one".