213221209 has 2 divisors, whose sum is σ = 213221210. Its totient is φ = 213221208.

The previous prime is 213221171. The next prime is 213221243. The reversal of 213221209 is 902122312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 212576400 + 644809 = 14580^2 + 803^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-213221209 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 213221209.

It is not a weakly prime, because it can be changed into another prime (213221909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106610604 + 106610605.

It is an arithmetic number, because the mean of its divisors is an integer number (106610605).

Almost surely, 2^213221209 is an apocalyptic number.

It is an amenable number.

213221209 is a deficient number, since it is larger than the sum of its proper divisors (1).

213221209 is an equidigital number, since it uses as much as digits as its factorization.

213221209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 213221209 is about 14602.0960481706. The cubic root of 213221209 is about 597.4159323376.

The spelling of 213221209 in words is "two hundred thirteen million, two hundred twenty-one thousand, two hundred nine".