1221285817 has 2 divisors, whose sum is σ = 1221285818. Its totient is φ = 1221285816.

The previous prime is 1221285799. The next prime is 1221285829. The reversal of 1221285817 is 7185821221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 796142656 + 425143161 = 28216^2 + 20619^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221285817 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221285217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610642908 + 610642909.

It is an arithmetic number, because the mean of its divisors is an integer number (610642909).

Almost surely, 2^1221285817 is an apocalyptic number.

It is an amenable number.

1221285817 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221285817 is an equidigital number, since it uses as much as digits as its factorization.

1221285817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17920, while the sum is 37.

The square root of 1221285817 is about 34946.8999626576. The cubic root of 1221285817 is about 1068.9049900640.

The spelling of 1221285817 in words is "one billion, two hundred twenty-one million, two hundred eighty-five thousand, eight hundred seventeen".