331220209 has 2 divisors, whose sum is σ = 331220210. Its totient is φ = 331220208.

The previous prime is 331220147. The next prime is 331220243. The reversal of 331220209 is 902022133.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 317552400 + 13667809 = 17820^2 + 3697^2 .

It is an emirp because it is prime and its reverse (902022133) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 331220209 - 2⁷ = 331220081 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 331220209.

It is not a weakly prime, because it can be changed into another prime (331220249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165610104 + 165610105.

It is an arithmetic number, because the mean of its divisors is an integer number (165610105).

Almost surely, 2^331220209 is an apocalyptic number.

It is an amenable number.

331220209 is a deficient number, since it is larger than the sum of its proper divisors (1).

331220209 is an equidigital number, since it uses as much as digits as its factorization.

331220209 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 22.

The square root of 331220209 is about 18199.4562830871. The cubic root of 331220209 is about 691.8930087575.

The spelling of 331220209 in words is "three hundred thirty-one million, two hundred twenty thousand, two hundred nine".