66709978609 has 16 divisors (see below), whose sum is σ = 70408880640. Its totient is φ = 63134256640.

The previous prime is 66709978603. The next prime is 66709978631. The reversal of 66709978609 is 90687990766.

It is a cyclic number.

It is not a de Polignac number, because 66709978609 - 2¹³ = 66709970417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66709978603) 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, 64572 + ... + 370930.

It is an arithmetic number, because the mean of its divisors is an integer number (4400555040).

Almost surely, 2^66709978609 is an apocalyptic number.

It is an amenable number.

66709978609 is a deficient number, since it is larger than the sum of its proper divisors (3698902031).

66709978609 is a wasteful number, since it uses less digits than its factorization.

66709978609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306560.

The product of its (nonzero) digits is 61725888, while the sum is 67.

The spelling of 66709978609 in words is "sixty-six billion, seven hundred nine million, nine hundred seventy-eight thousand, six hundred nine".