1211221309 has 2 divisors, whose sum is σ = 1211221310. Its totient is φ = 1211221308.

The previous prime is 1211221237. The next prime is 1211221313. The reversal of 1211221309 is 9031221121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 701455225 + 509766084 = 26485^2 + 22578^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211221309 - 2¹³ = 1211213117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1211221309.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211221409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605610654 + 605610655.

It is an arithmetic number, because the mean of its divisors is an integer number (605610655).

Almost surely, 2^1211221309 is an apocalyptic number.

It is an amenable number.

1211221309 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211221309 is an equidigital number, since it uses as much as digits as its factorization.

1211221309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 1211221309 is about 34802.6049168737. The cubic root of 1211221309 is about 1065.9606367620.

The spelling of 1211221309 in words is "one billion, two hundred eleven million, two hundred twenty-one thousand, three hundred nine".