312123209 has 2 divisors, whose sum is σ = 312123210. Its totient is φ = 312123208.

The previous prime is 312123187. The next prime is 312123211. The reversal of 312123209 is 902321213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 298321984 + 13801225 = 17272^2 + 3715^2 .

It is an emirp because it is prime and its reverse (902321213) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 312123209 - 2¹² = 312119113 is a prime.

It is a Sophie Germain prime.

Together with 312123211, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (312123239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 156061604 + 156061605.

It is an arithmetic number, because the mean of its divisors is an integer number (156061605).

Almost surely, 2^312123209 is an apocalyptic number.

It is an amenable number.

312123209 is a deficient number, since it is larger than the sum of its proper divisors (1).

312123209 is an equidigital number, since it uses as much as digits as its factorization.

312123209 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 23.

The square root of 312123209 is about 17667.0090564306. The cubic root of 312123209 is about 678.3315562914.

The spelling of 312123209 in words is "three hundred twelve million, one hundred twenty-three thousand, two hundred nine".