21742953209 has 2 divisors, whose sum is σ = 21742953210. Its totient is φ = 21742953208.

The previous prime is 21742953191. The next prime is 21742953283. The reversal of 21742953209 is 90235924712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12785277184 + 8957676025 = 113072^2 + 94645^2 .

It is a cyclic number.

It is not a de Polignac number, because 21742953209 - 2³² = 17447985913 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21742953209.

It is not a weakly prime, because it can be changed into another prime (21742953809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10871476604 + 10871476605.

It is an arithmetic number, because the mean of its divisors is an integer number (10871476605).

Almost surely, 2^21742953209 is an apocalyptic number.

It is an amenable number.

21742953209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21742953209 is an equidigital number, since it uses as much as digits as its factorization.

21742953209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 272160, while the sum is 44.

The spelling of 21742953209 in words is "twenty-one billion, seven hundred forty-two million, nine hundred fifty-three thousand, two hundred nine".