168959981 has 2 divisors, whose sum is σ = 168959982. Its totient is φ = 168959980.

The previous prime is 168959977. The next prime is 168960037. The reversal of 168959981 is 189959861.

It is an a-pointer prime, because the next prime (168960037) can be obtained adding 168959981 to its sum of digits (56).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 157904356 + 11055625 = 12566^2 + 3325^2 .

It is a cyclic number.

It is not a de Polignac number, because 168959981 - 2² = 168959977 is a prime.

It is a super-2 number, since 2×168959981² = 57094950359040722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (168959881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84479990 + 84479991.

It is an arithmetic number, because the mean of its divisors is an integer number (84479991).

Almost surely, 2^168959981 is an apocalyptic number.

It is an amenable number.

168959981 is a deficient number, since it is larger than the sum of its proper divisors (1).

168959981 is an equidigital number, since it uses as much as digits as its factorization.

168959981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1399680, while the sum is 56.

The square root of 168959981 is about 12998.4607165618. The cubic root of 168959981 is about 552.8338376783.

The spelling of 168959981 in words is "one hundred sixty-eight million, nine hundred fifty-nine thousand, nine hundred eighty-one".