6721661065571 has 4 divisors (see below), whose sum is σ = 6736054344552. Its totient is φ = 6707267786592.

The previous prime is 6721661065529. The next prime is 6721661065573. The reversal of 6721661065571 is 1755601661276.

6721661065571 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 6721661065571 - 2⁶ = 6721661065507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6721661065573) 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, 7196638790 + ... + 7196639723.

It is an arithmetic number, because the mean of its divisors is an integer number (1684013586138).

Almost surely, 2^{6721661065571} is an apocalyptic number.

6721661065571 is a deficient number, since it is larger than the sum of its proper divisors (14393278981).

6721661065571 is a wasteful number, since it uses less digits than its factorization.

6721661065571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14393278980.

The product of its (nonzero) digits is 3175200, while the sum is 53.

The spelling of 6721661065571 in words is "six trillion, seven hundred twenty-one billion, six hundred sixty-one million, sixty-five thousand, five hundred seventy-one".