664420121 has 2 divisors, whose sum is σ = 664420122. Its totient is φ = 664420120.

The previous prime is 664420109. The next prime is 664420123. The reversal of 664420121 is 121024466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 400000000 + 264420121 = 20000^2 + 16261^2 .

It is a cyclic number.

It is not a de Polignac number, because 664420121 - 2¹⁰ = 664419097 is a prime.

Together with 664420123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (664420123) 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, 332210060 + 332210061.

It is an arithmetic number, because the mean of its divisors is an integer number (332210061).

Almost surely, 2^664420121 is an apocalyptic number.

It is an amenable number.

664420121 is a deficient number, since it is larger than the sum of its proper divisors (1).

664420121 is an equidigital number, since it uses as much as digits as its factorization.

664420121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 664420121 is about 25776.3480927768. The cubic root of 664420121 is about 872.5980912313.

Adding to 664420121 its reverse (121024466), we get a palindrome (785444587).

The spelling of 664420121 in words is "six hundred sixty-four million, four hundred twenty thousand, one hundred twenty-one".