1221220212857 has 2 divisors, whose sum is σ = 1221220212858. Its totient is φ = 1221220212856.

The previous prime is 1221220212847. The next prime is 1221220212907. The reversal of 1221220212857 is 7582120221221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1187465704681 + 33754508176 = 1089709^2 + 183724^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221220212857 - 2⁸ = 1221220212601 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221220212827) 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, 610610106428 + 610610106429.

It is an arithmetic number, because the mean of its divisors is an integer number (610610106429).

Almost surely, 2^{1221220212857} is an apocalyptic number.

It is an amenable number.

1221220212857 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221220212857 is an equidigital number, since it uses as much as digits as its factorization.

1221220212857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17920, while the sum is 35.

The spelling of 1221220212857 in words is "one trillion, two hundred twenty-one billion, two hundred twenty million, two hundred twelve thousand, eight hundred fifty-seven".