168917561 has 2 divisors, whose sum is σ = 168917562. Its totient is φ = 168917560.

The previous prime is 168917549. The next prime is 168917569. The reversal of 168917561 is 165719861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 107765161 + 61152400 = 10381^2 + 7820^2 .

It is an emirp because it is prime and its reverse (165719861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 168917561 - 2¹⁴ = 168901177 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (168917569) 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, 84458780 + 84458781.

It is an arithmetic number, because the mean of its divisors is an integer number (84458781).

Almost surely, 2^168917561 is an apocalyptic number.

It is an amenable number.

168917561 is a deficient number, since it is larger than the sum of its proper divisors (1).

168917561 is an equidigital number, since it uses as much as digits as its factorization.

168917561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 44.

The square root of 168917561 is about 12996.8288824621. The cubic root of 168917561 is about 552.7875679954.

The spelling of 168917561 in words is "one hundred sixty-eight million, nine hundred seventeen thousand, five hundred sixty-one".