21445709609 has 2 divisors, whose sum is σ = 21445709610. Its totient is φ = 21445709608.

The previous prime is 21445709563. The next prime is 21445709639. The reversal of 21445709609 is 90690754412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17756362009 + 3689347600 = 133253^2 + 60740^2 .

It is a cyclic number.

It is not a de Polignac number, because 21445709609 - 2⁸ = 21445709353 is a prime.

It is not a weakly prime, because it can be changed into another prime (21445709639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722854804 + 10722854805.

It is an arithmetic number, because the mean of its divisors is an integer number (10722854805).

Almost surely, 2^21445709609 is an apocalyptic number.

It is an amenable number.

21445709609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21445709609 is an equidigital number, since it uses as much as digits as its factorization.

21445709609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 544320, while the sum is 47.

The spelling of 21445709609 in words is "twenty-one billion, four hundred forty-five million, seven hundred nine thousand, six hundred nine".