21232218209 has 2 divisors, whose sum is σ = 21232218210. Its totient is φ = 21232218208.

The previous prime is 21232218197. The next prime is 21232218239. The reversal of 21232218209 is 90281223212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21111218209 + 121000000 = 145297^2 + 11000^2 .

It is a cyclic number.

It is not a de Polignac number, because 21232218209 - 2²⁴ = 21215440993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21232218239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10616109104 + 10616109105.

It is an arithmetic number, because the mean of its divisors is an integer number (10616109105).

Almost surely, 2^21232218209 is an apocalyptic number.

It is an amenable number.

21232218209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21232218209 is an equidigital number, since it uses as much as digits as its factorization.

21232218209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 32.

The spelling of 21232218209 in words is "twenty-one billion, two hundred thirty-two million, two hundred eighteen thousand, two hundred nine".