28066801391721 has 27 divisors (see below), whose sum is σ = 40728691658109. Its totient is φ = 18624941969112.

The previous prime is 28066801391711. The next prime is 28066801391743. The reversal of 28066801391721 is 12719310866082.

The square root of 28066801391721 is 5297811.

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

28066801391721 is a `hidden beast` number, since 280 + 6 + 68 + 0 + 139 + 172 + 1 = 666.

It is not a de Polignac number, because 28066801391721 - 2¹¹ = 28066801389673 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28066801391701) 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 26 ways as a sum of consecutive naturals, for example, 3544231600 + ... + 3544239518.

Almost surely, 2^{28066801391721} is an apocalyptic number.

28066801391721 is the 5297811-st square number.

28066801391721 is the 2648906-th centered octagonal number.

It is an amenable number.

28066801391721 is a deficient number, since it is larger than the sum of its proper divisors (12661890266388).

28066801391721 is an frugal number, since it uses more digits than its factorization.

28066801391721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16290 (or 8145 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 54.

It can be divided in two parts, 2806680 and 1391721, that added together give a square (4198401 = 2049²).

The spelling of 28066801391721 in words is "twenty-eight trillion, sixty-six billion, eight hundred one million, three hundred ninety-one thousand, seven hundred twenty-one".