168897991 has 2 divisors, whose sum is σ = 168897992. Its totient is φ = 168897990.

The previous prime is 168897979. The next prime is 168898003. The reversal of 168897991 is 199798861.

It is a balanced prime because it is at equal distance from previous prime (168897979) and next prime (168898003).

It is a cyclic number.

It is not a de Polignac number, because 168897991 - 2¹⁷ = 168766919 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (168897961) 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, 84448995 + 84448996.

It is an arithmetic number, because the mean of its divisors is an integer number (84448996).

Almost surely, 2^168897991 is an apocalyptic number.

168897991 is a deficient number, since it is larger than the sum of its proper divisors (1).

168897991 is an equidigital number, since it uses as much as digits as its factorization.

168897991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1959552, while the sum is 58.

The square root of 168897991 is about 12996.0759846963. The cubic root of 168897991 is about 552.7662193753.

The spelling of 168897991 in words is "one hundred sixty-eight million, eight hundred ninety-seven thousand, nine hundred ninety-one".