168991937 has 2 divisors, whose sum is σ = 168991938. Its totient is φ = 168991936.

The previous prime is 168991897. The next prime is 168991939. The reversal of 168991937 is 739199861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 92236816 + 76755121 = 9604^2 + 8761^2 .

It is an emirp because it is prime and its reverse (739199861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 168991937 - 2²⁴ = 152214721 is a prime.

Together with 168991939, 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 (168991939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84495968 + 84495969.

It is an arithmetic number, because the mean of its divisors is an integer number (84495969).

Almost surely, 2^168991937 is an apocalyptic number.

It is an amenable number.

168991937 is a deficient number, since it is larger than the sum of its proper divisors (1).

168991937 is an equidigital number, since it uses as much as digits as its factorization.

168991937 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 734832, while the sum is 53.

The square root of 168991937 is about 12999.6898809164. The cubic root of 168991937 is about 552.8686886223.

The spelling of 168991937 in words is "one hundred sixty-eight million, nine hundred ninety-one thousand, nine hundred thirty-seven".