6721457566 has 4 divisors (see below), whose sum is σ = 10082186352. Its totient is φ = 3360728782.

The previous prime is 6721457563. The next prime is 6721457597. The reversal of 6721457566 is 6657541276.

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

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6721457563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1680364390 + ... + 1680364393.

It is an arithmetic number, because the mean of its divisors is an integer number (2520546588).

Almost surely, 2^6721457566 is an apocalyptic number.

6721457566 is a deficient number, since it is larger than the sum of its proper divisors (3360728786).

6721457566 is a wasteful number, since it uses less digits than its factorization.

6721457566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3360728785.

The product of its digits is 2116800, while the sum is 49.

The square root of 6721457566 is about 81984.4958879421. The cubic root of 6721457566 is about 1887.2140177862.

The spelling of 6721457566 in words is "six billion, seven hundred twenty-one million, four hundred fifty-seven thousand, five hundred sixty-six".