168736921 has 2 divisors, whose sum is σ = 168736922. Its totient is φ = 168736920.

The previous prime is 168736903. The next prime is 168736927. The reversal of 168736921 is 129637861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 157251600 + 11485321 = 12540^2 + 3389^2 .

It is an emirp because it is prime and its reverse (129637861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 168736921 - 2¹⁹ = 168212633 is a prime.

It is not a weakly prime, because it can be changed into another prime (168736927) 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, 84368460 + 84368461.

It is an arithmetic number, because the mean of its divisors is an integer number (84368461).

Almost surely, 2^168736921 is an apocalyptic number.

It is an amenable number.

168736921 is a deficient number, since it is larger than the sum of its proper divisors (1).

168736921 is an equidigital number, since it uses as much as digits as its factorization.

168736921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 43.

The square root of 168736921 is about 12989.8776360672. The cubic root of 168736921 is about 552.5904478500.

The spelling of 168736921 in words is "one hundred sixty-eight million, seven hundred thirty-six thousand, nine hundred twenty-one".