664126311221 has 2 divisors, whose sum is σ = 664126311222. Its totient is φ = 664126311220.

The previous prime is 664126311203. The next prime is 664126311227. The reversal of 664126311221 is 122113621466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 436583955025 + 227542356196 = 660745^2 + 477014^2 .

It is a cyclic number.

It is not a de Polignac number, because 664126311221 - 2¹⁴ = 664126294837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664126311227) 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, 332063155610 + 332063155611.

It is an arithmetic number, because the mean of its divisors is an integer number (332063155611).

Almost surely, 2^664126311221 is an apocalyptic number.

It is an amenable number.

664126311221 is a deficient number, since it is larger than the sum of its proper divisors (1).

664126311221 is an equidigital number, since it uses as much as digits as its factorization.

664126311221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 35.

Adding to 664126311221 its reverse (122113621466), we get a palindrome (786239932687).

The spelling of 664126311221 in words is "six hundred sixty-four billion, one hundred twenty-six million, three hundred eleven thousand, two hundred twenty-one".