664121 has 2 divisors, whose sum is σ = 664122. Its totient is φ = 664120.

The previous prime is 664117. The next prime is 664123. The reversal of 664121 is 121466.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 657721 + 6400 = 811^2 + 80^2 .

It is a cyclic number.

It is not a de Polignac number, because 664121 - 2² = 664117 is a prime.

Together with 664123, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 664093 and 664102.

It is not a weakly prime, because it can be changed into another prime (664123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332060 + 332061.

It is an arithmetic number, because the mean of its divisors is an integer number (332061).

2⁶⁶⁴¹²¹ is an apocalyptic number.

It is an amenable number.

664121 is a deficient number, since it is larger than the sum of its proper divisors (1).

664121 is an equidigital number, since it uses as much as digits as its factorization.

664121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 20.

The square root of 664121 is about 814.9361938213. The cubic root of 664121 is about 87.2467124100.

Adding to 664121 its reverse (121466), we get a palindrome (785587).

The spelling of 664121 in words is "six hundred sixty-four thousand, one hundred twenty-one".