1243400220221 has 2 divisors, whose sum is σ = 1243400220222. Its totient is φ = 1243400220220.

The previous prime is 1243400220211. The next prime is 1243400220247. The reversal of 1243400220221 is 1220220043421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 798529896025 + 444870324196 = 893605^2 + 666986^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243400220221 - 2¹⁰ = 1243400219197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1243400220211) 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, 621700110110 + 621700110111.

It is an arithmetic number, because the mean of its divisors is an integer number (621700110111).

Almost surely, 2^{1243400220221} is an apocalyptic number.

It is an amenable number.

1243400220221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1243400220221 is an equidigital number, since it uses as much as digits as its factorization.

1243400220221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1536, while the sum is 23.

Adding to 1243400220221 its reverse (1220220043421), we get a palindrome (2463620263642).

The spelling of 1243400220221 in words is "one trillion, two hundred forty-three billion, four hundred million, two hundred twenty thousand, two hundred twenty-one".