1221221220997 has 2 divisors, whose sum is σ = 1221221220998. Its totient is φ = 1221221220996.

The previous prime is 1221221220983. The next prime is 1221221221009. The reversal of 1221221220997 is 7990221221221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 750118816836 + 471102404161 = 866094^2 + 686369^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221221220997 is a prime.

It is a super-2 number, since 2×1221221220997² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221221220697) 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, 610610610498 + 610610610499.

It is an arithmetic number, because the mean of its divisors is an integer number (610610610499).

Almost surely, 2^{1221221220997} is an apocalyptic number.

It is an amenable number.

1221221220997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221221220997 is an equidigital number, since it uses as much as digits as its factorization.

1221221220997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36288, while the sum is 40.

The spelling of 1221221220997 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, two hundred twenty thousand, nine hundred ninety-seven".