21211313209 has 2 divisors, whose sum is σ = 21211313210. Its totient is φ = 21211313208.

The previous prime is 21211313177. The next prime is 21211313251. The reversal of 21211313209 is 90231311212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21046755625 + 164557584 = 145075^2 + 12828^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211313209 - 2⁵ = 21211313177 is a prime.

It is not a weakly prime, because it can be changed into another prime (21211314209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605656604 + 10605656605.

It is an arithmetic number, because the mean of its divisors is an integer number (10605656605).

Almost surely, 2^21211313209 is an apocalyptic number.

It is an amenable number.

21211313209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211313209 is an equidigital number, since it uses as much as digits as its factorization.

21211313209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 25.

The spelling of 21211313209 in words is "twenty-one billion, two hundred eleven million, three hundred thirteen thousand, two hundred nine".