21220999609 has 2 divisors, whose sum is σ = 21220999610. Its totient is φ = 21220999608.

The previous prime is 21220999601. The next prime is 21220999627. The reversal of 21220999609 is 90699902212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18693725625 + 2527273984 = 136725^2 + 50272^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220999609 - 2³ = 21220999601 is a prime.

It is not a weakly prime, because it can be changed into another prime (21220999601) 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, 10610499804 + 10610499805.

It is an arithmetic number, because the mean of its divisors is an integer number (10610499805).

Almost surely, 2^21220999609 is an apocalyptic number.

It is an amenable number.

21220999609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220999609 is an equidigital number, since it uses as much as digits as its factorization.

21220999609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 314928, while the sum is 49.

The spelling of 21220999609 in words is "twenty-one billion, two hundred twenty million, nine hundred ninety-nine thousand, six hundred nine".