168193721 has 2 divisors, whose sum is σ = 168193722. Its totient is φ = 168193720.

The previous prime is 168193717. The next prime is 168193783. The reversal of 168193721 is 127391861.

168193721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 99900025 + 68293696 = 9995^2 + 8264^2 .

It is an emirp because it is prime and its reverse (127391861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 168193721 - 2² = 168193717 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (168103721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84096860 + 84096861.

It is an arithmetic number, because the mean of its divisors is an integer number (84096861).

Almost surely, 2^168193721 is an apocalyptic number.

It is an amenable number.

168193721 is a deficient number, since it is larger than the sum of its proper divisors (1).

168193721 is an equidigital number, since it uses as much as digits as its factorization.

168193721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 38.

The square root of 168193721 is about 12968.9521936045. The cubic root of 168193721 is about 551.9968417256.

The spelling of 168193721 in words is "one hundred sixty-eight million, one hundred ninety-three thousand, seven hundred twenty-one".