1221203309 has 2 divisors, whose sum is σ = 1221203310. Its totient is φ = 1221203308.

The previous prime is 1221203297. The next prime is 1221203351. The reversal of 1221203309 is 9033021221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 726140809 + 495062500 = 26947^2 + 22250^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221203309 - 2⁴ = 1221203293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221203909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610601654 + 610601655.

It is an arithmetic number, because the mean of its divisors is an integer number (610601655).

Almost surely, 2^1221203309 is an apocalyptic number.

It is an amenable number.

1221203309 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221203309 is an equidigital number, since it uses as much as digits as its factorization.

1221203309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 1221203309 is about 34945.7194660519. The cubic root of 1221203309 is about 1068.8809183854.

The spelling of 1221203309 in words is "one billion, two hundred twenty-one million, two hundred three thousand, three hundred nine".