6722668881721 has 9 divisors (see below), whose sum is σ = 7279612862031. Its totient is φ = 6205509392472.

The previous prime is 6722668881703. The next prime is 6722668881727. The reversal of 6722668881721 is 1271888662276.

The square root of 6722668881721 is 2592811.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 994477645225 + 5728191236496 = 997235^2 + 2393364^2 .

It is not a de Polignac number, because 6722668881721 - 2⁵ = 6722668881689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6722668881727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 33606820 + ... + 33806266.

It is an arithmetic number, because the mean of its divisors is an integer number (808845873559).

Almost surely, 2^{6722668881721} is an apocalyptic number.

6722668881721 is the 2592811-st square number.

6722668881721 is the 1296406-th centered octagonal number.

It is an amenable number.

6722668881721 is a deficient number, since it is larger than the sum of its proper divisors (556943980310).

6722668881721 is an frugal number, since it uses more digits than its factorization.

6722668881721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398920 (or 199460 counting only the distinct ones).

The product of its digits is 43352064, while the sum is 64.

Multiplying 6722668881721 by its sum of digits (64), we get a square (430250808430144 = 20742488²).

The spelling of 6722668881721 in words is "six trillion, seven hundred twenty-two billion, six hundred sixty-eight million, eight hundred eighty-one thousand, seven hundred twenty-one".