21211430209 has 2 divisors, whose sum is σ = 21211430210. Its totient is φ = 21211430208.

The previous prime is 21211430203. The next prime is 21211430267. The reversal of 21211430209 is 90203411212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16562917809 + 4648512400 = 128697^2 + 68180^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211430209 is a prime.

It is a super-2 number, since 2×21211430209² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21211430203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605715104 + 10605715105.

It is an arithmetic number, because the mean of its divisors is an integer number (10605715105).

Almost surely, 2^21211430209 is an apocalyptic number.

It is an amenable number.

21211430209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211430209 is an equidigital number, since it uses as much as digits as its factorization.

21211430209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 25.

The spelling of 21211430209 in words is "twenty-one billion, two hundred eleven million, four hundred thirty thousand, two hundred nine".