1221704909 has 2 divisors, whose sum is σ = 1221704910. Its totient is φ = 1221704908.

The previous prime is 1221704873. The next prime is 1221704941. The reversal of 1221704909 is 9094071221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 910711684 + 310993225 = 30178^2 + 17635^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221704909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221704969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610852454 + 610852455.

It is an arithmetic number, because the mean of its divisors is an integer number (610852455).

Almost surely, 2^1221704909 is an apocalyptic number.

It is an amenable number.

1221704909 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221704909 is an equidigital number, since it uses as much as digits as its factorization.

1221704909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 35.

The square root of 1221704909 is about 34952.8955739006. The cubic root of 1221704909 is about 1069.0272432643.

The spelling of 1221704909 in words is "one billion, two hundred twenty-one million, seven hundred four thousand, nine hundred nine".