21729655393 has 8 divisors (see below), whose sum is σ = 21774379176. Its totient is φ = 21684960000.

The previous prime is 21729655379. The next prime is 21729655397. The reversal of 21729655393 is 39355692712.

It can be written as a sum of positive squares in 4 ways, for example, as 8885513169 + 12844142224 = 94263^2 + 113332^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21729655393 - 2⁵ = 21729655361 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21729655393.

It is not an unprimeable number, because it can be changed into a prime (21729655397) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2189743 + ... + 2199643.

It is an arithmetic number, because the mean of its divisors is an integer number (2721797397).

Almost surely, 2^21729655393 is an apocalyptic number.

It is an amenable number.

21729655393 is a deficient number, since it is larger than the sum of its proper divisors (44723783).

21729655393 is an equidigital number, since it uses as much as digits as its factorization.

21729655393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14195.

The product of its digits is 3061800, while the sum is 52.

The spelling of 21729655393 in words is "twenty-one billion, seven hundred twenty-nine million, six hundred fifty-five thousand, three hundred ninety-three".