1221220212257 has 2 divisors, whose sum is σ = 1221220212258. Its totient is φ = 1221220212256.

The previous prime is 1221220212211. The next prime is 1221220212263. The reversal of 1221220212257 is 7522120221221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1068889244641 + 152330967616 = 1033871^2 + 390296^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221220212257 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221220212857) 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, 610610106128 + 610610106129.

It is an arithmetic number, because the mean of its divisors is an integer number (610610106129).

Almost surely, 2^{1221220212257} is an apocalyptic number.

It is an amenable number.

1221220212257 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221220212257 is an equidigital number, since it uses as much as digits as its factorization.

1221220212257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4480, while the sum is 29.

Adding to 1221220212257 its reverse (7522120221221), we get a palindrome (8743340433478).

The spelling of 1221220212257 in words is "one trillion, two hundred twenty-one billion, two hundred twenty million, two hundred twelve thousand, two hundred fifty-seven".