21728202722 has 6 divisors (see below), whose sum is σ = 32592616779. Its totient is φ = 10863997130.

The previous prime is 21728202721. The next prime is 21728202731. The reversal of 21728202722 is 22720282712.

It can be written as a sum of positive squares in only one way, i.e., 10864101361 + 10864101361 = 104231^2 + 104231^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=104231.

It is a super-2 number, since 2×21728202722² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21728202721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 156347 + ... + 260577.

Almost surely, 2^21728202722 is an apocalyptic number.

21728202722 is a deficient number, since it is larger than the sum of its proper divisors (10864414057).

21728202722 is an frugal number, since it uses more digits than its factorization.

21728202722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208464 (or 104233 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 35.

Multiplying 21728202722 by its product of nonzero digits (25088), we get a square (545117149889536 = 23347744²).

The spelling of 21728202722 in words is "twenty-one billion, seven hundred twenty-eight million, two hundred two thousand, seven hundred twenty-two".