212909 has 2 divisors, whose sum is σ = 212910. Its totient is φ = 212908.

The previous prime is 212903. The next prime is 212917. The reversal of 212909 is 909212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 198025 + 14884 = 445^2 + 122^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-212909 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (212903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106454 + 106455.

It is an arithmetic number, because the mean of its divisors is an integer number (106455).

2²¹²⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

212909 is a deficient number, since it is larger than the sum of its proper divisors (1).

212909 is an equidigital number, since it uses as much as digits as its factorization.

212909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 212909 is about 461.4206323952. The cubic root of 212909 is about 59.7124201288.

The spelling of 212909 in words is "two hundred twelve thousand, nine hundred nine".