21232131209 has 2 divisors, whose sum is σ = 21232131210. Its totient is φ = 21232131208.

The previous prime is 21232131203. The next prime is 21232131211. The reversal of 21232131209 is 90213123212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12084165184 + 9147966025 = 109928^2 + 95645^2 .

It is a cyclic number.

It is not a de Polignac number, because 21232131209 - 2²⁴ = 21215353993 is a prime.

Together with 21232131211, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21232131203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10616065604 + 10616065605.

It is an arithmetic number, because the mean of its divisors is an integer number (10616065605).

Almost surely, 2^21232131209 is an apocalyptic number.

It is an amenable number.

21232131209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21232131209 is an equidigital number, since it uses as much as digits as its factorization.

21232131209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 26.

The spelling of 21232131209 in words is "twenty-one billion, two hundred thirty-two million, one hundred thirty-one thousand, two hundred nine".