66639769812 has 144 divisors (see below), whose sum is σ = 210126239232. Its totient is φ = 17299967040.

The previous prime is 66639769793. The next prime is 66639769883. The reversal of 66639769812 is 21896793666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a self number, because there is not a number n which added to its sum of digits gives 66639769812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6500763 + ... + 6511005.

Almost surely, 2^66639769812 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66639769812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105063119616).

66639769812 is an abundant number, since it is smaller than the sum of its proper divisors (143486469420).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66639769812 is a wasteful number, since it uses less digits than its factorization.

66639769812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12618 (or 12613 counting only the distinct ones).

The product of its digits is 35271936, while the sum is 63.

The spelling of 66639769812 in words is "sixty-six billion, six hundred thirty-nine million, seven hundred sixty-nine thousand, eight hundred twelve".