168791681 has 2 divisors, whose sum is σ = 168791682. Its totient is φ = 168791680.

The previous prime is 168791677. The next prime is 168791713. The reversal of 168791681 is 186197861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 168766081 + 25600 = 12991^2 + 160^2 .

It is a cyclic number.

It is not a de Polignac number, because 168791681 - 2² = 168791677 is a prime.

It is a super-2 number, since 2×168791681² = 56981263149611522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (168781681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84395840 + 84395841.

It is an arithmetic number, because the mean of its divisors is an integer number (84395841).

Almost surely, 2^168791681 is an apocalyptic number.

It is an amenable number.

168791681 is a deficient number, since it is larger than the sum of its proper divisors (1).

168791681 is an equidigital number, since it uses as much as digits as its factorization.

168791681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 47.

The square root of 168791681 is about 12991.9852601517. The cubic root of 168791681 is about 552.6502185667.

The spelling of 168791681 in words is "one hundred sixty-eight million, seven hundred ninety-one thousand, six hundred eighty-one".