66656434709 has 4 divisors (see below), whose sum is σ = 66747371916. Its totient is φ = 66565497504.

The previous prime is 66656434681. The next prime is 66656434807. The reversal of 66656434709 is 90743465666.

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

It can be written as a sum of positive squares in 2 ways, for example, as 65264920900 + 1391513809 = 255470^2 + 37303^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66656434709 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66656434909) 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, 45467504 + ... + 45468969.

It is an arithmetic number, because the mean of its divisors is an integer number (16686842979).

Almost surely, 2^66656434709 is an apocalyptic number.

It is an amenable number.

66656434709 is a deficient number, since it is larger than the sum of its proper divisors (90937207).

66656434709 is an equidigital number, since it uses as much as digits as its factorization.

66656434709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90937206.

The product of its (nonzero) digits is 19595520, while the sum is 56.

The spelling of 66656434709 in words is "sixty-six billion, six hundred fifty-six million, four hundred thirty-four thousand, seven hundred nine".