21243411109 has 2 divisors, whose sum is σ = 21243411110. Its totient is φ = 21243411108.

The previous prime is 21243411097. The next prime is 21243411227. The reversal of 21243411109 is 90111434212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21017750625 + 225660484 = 144975^2 + 15022^2 .

It is a cyclic number.

It is not a de Polignac number, because 21243411109 - 2²¹ = 21241313957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21243421109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621705554 + 10621705555.

It is an arithmetic number, because the mean of its divisors is an integer number (10621705555).

Almost surely, 2^21243411109 is an apocalyptic number.

It is an amenable number.

21243411109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243411109 is an equidigital number, since it uses as much as digits as its factorization.

21243411109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 28.

The spelling of 21243411109 in words is "twenty-one billion, two hundred forty-three million, four hundred eleven thousand, one hundred nine".