7947720666 has 48 divisors (see below), whose sum is σ = 17791937280. Its totient is φ = 2561417280.

The previous prime is 7947720619. The next prime is 7947720689. The reversal of 7947720666 is 6660277497.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 659725 + ... + 671663.

It is an arithmetic number, because the mean of its divisors is an integer number (370665360).

Almost surely, 2^7947720666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7947720666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8895968640).

7947720666 is an abundant number, since it is smaller than the sum of its proper divisors (9844216614).

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

7947720666 is a wasteful number, since it uses less digits than its factorization.

7947720666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13171 (or 13168 counting only the distinct ones).

The product of its (nonzero) digits is 5334336, while the sum is 54.

The square root of 7947720666 is about 89149.9897139646. The cubic root of 7947720666 is about 1995.6338641984.

The spelling of 7947720666 in words is "seven billion, nine hundred forty-seven million, seven hundred twenty thousand, six hundred sixty-six".