21221741609 has 2 divisors, whose sum is σ = 21221741610. Its totient is φ = 21221741608.

The previous prime is 21221741587. The next prime is 21221741617. The reversal of 21221741609 is 90614712212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20226528400 + 995213209 = 142220^2 + 31547^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221741609 - 2²⁰ = 21220693033 is a prime.

It is not a weakly prime, because it can be changed into another prime (21221741659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610870804 + 10610870805.

It is an arithmetic number, because the mean of its divisors is an integer number (10610870805).

Almost surely, 2^21221741609 is an apocalyptic number.

It is an amenable number.

21221741609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221741609 is an equidigital number, since it uses as much as digits as its factorization.

21221741609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 35.

The spelling of 21221741609 in words is "twenty-one billion, two hundred twenty-one million, seven hundred forty-one thousand, six hundred nine".