6721706666 has 8 divisors (see below), whose sum is σ = 10195847460. Its totient is φ = 3323090848.

The previous prime is 6721706573. The next prime is 6721706669. The reversal of 6721706666 is 6666071276.

It can be written as a sum of positive squares in 2 ways, for example, as 6501035641 + 220671025 = 80629^2 + 14855^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 6721706666.

It is not an unprimeable number, because it can be changed into a prime (6721706669) 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, 18881021 + ... + 18881376.

Almost surely, 2^6721706666 is an apocalyptic number.

6721706666 is a deficient number, since it is larger than the sum of its proper divisors (3474140794).

6721706666 is a wasteful number, since it uses less digits than its factorization.

6721706666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37762488.

The product of its (nonzero) digits is 762048, while the sum is 47.

The square root of 6721706666 is about 81986.0150635461. The cubic root of 6721706666 is about 1887.2373311425.

The spelling of 6721706666 in words is "six billion, seven hundred twenty-one million, seven hundred six thousand, six hundred sixty-six".