168216121 has 2 divisors, whose sum is σ = 168216122. Its totient is φ = 168216120.

The previous prime is 168216119. The next prime is 168216161. The reversal of 168216121 is 121612861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 104040000 + 64176121 = 10200^2 + 8011^2 .

It is an emirp because it is prime and its reverse (121612861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 168216121 - 2¹ = 168216119 is a prime.

Together with 168216119, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 168216121.

It is not a weakly prime, because it can be changed into another prime (168216161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84108060 + 84108061.

It is an arithmetic number, because the mean of its divisors is an integer number (84108061).

Almost surely, 2^168216121 is an apocalyptic number.

It is an amenable number.

168216121 is a deficient number, since it is larger than the sum of its proper divisors (1).

168216121 is an equidigital number, since it uses as much as digits as its factorization.

168216121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 28.

The square root of 168216121 is about 12969.8157658465. The cubic root of 168216121 is about 552.0213455741.

Adding to 168216121 its reverse (121612861), we get a palindrome (289828982).

The spelling of 168216121 in words is "one hundred sixty-eight million, two hundred sixteen thousand, one hundred twenty-one".