231228209 has 2 divisors, whose sum is σ = 231228210. Its totient is φ = 231228208.

The previous prime is 231228199. The next prime is 231228211. The reversal of 231228209 is 902822132.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 185368225 + 45859984 = 13615^2 + 6772^2 .

It is a cyclic number.

It is not a de Polignac number, because 231228209 - 2¹² = 231224113 is a prime.

Together with 231228211, it forms a pair of twin primes.

It is a Chen prime.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (231228259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115614104 + 115614105.

It is an arithmetic number, because the mean of its divisors is an integer number (115614105).

Almost surely, 2^231228209 is an apocalyptic number.

It is an amenable number.

231228209 is a deficient number, since it is larger than the sum of its proper divisors (1).

231228209 is an equidigital number, since it uses as much as digits as its factorization.

231228209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 231228209 is about 15206.1898251995. The cubic root of 231228209 is about 613.7812327399.

The spelling of 231228209 in words is "two hundred thirty-one million, two hundred twenty-eight thousand, two hundred nine".