1221122219921 has 2 divisors, whose sum is σ = 1221122219922. Its totient is φ = 1221122219920.

The previous prime is 1221122219873. The next prime is 1221122220061. The reversal of 1221122219921 is 1299122211221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1017869121025 + 203253098896 = 1008895^2 + 450836^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221122219921 is a prime.

It is a super-2 number, since 2×1221122219921² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1221122219021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610561109960 + 610561109961.

It is an arithmetic number, because the mean of its divisors is an integer number (610561109961).

Almost surely, 2^{1221122219921} is an apocalyptic number.

It is an amenable number.

1221122219921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221122219921 is an equidigital number, since it uses as much as digits as its factorization.

1221122219921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 35.

The spelling of 1221122219921 in words is "one trillion, two hundred twenty-one billion, one hundred twenty-two million, two hundred nineteen thousand, nine hundred twenty-one".