168238981 has 2 divisors, whose sum is σ = 168238982. Its totient is φ = 168238980.

The previous prime is 168238979. The next prime is 168239003. The reversal of 168238981 is 189832861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 167288356 + 950625 = 12934^2 + 975^2 .

It is an emirp because it is prime and its reverse (189832861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 168238981 - 2¹ = 168238979 is a prime.

It is a super-2 number, since 2×168238981² = 56608709455836722, which contains 22 as substring.

Together with 168238979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (168238181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84119490 + 84119491.

It is an arithmetic number, because the mean of its divisors is an integer number (84119491).

Almost surely, 2^168238981 is an apocalyptic number.

It is an amenable number.

168238981 is a deficient number, since it is larger than the sum of its proper divisors (1).

168238981 is an equidigital number, since it uses as much as digits as its factorization.

168238981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 165888, while the sum is 46.

The square root of 168238981 is about 12970.6970128825. The cubic root of 168238981 is about 552.0463503840.

The spelling of 168238981 in words is "one hundred sixty-eight million, two hundred thirty-eight thousand, nine hundred eighty-one".