168861661 has 2 divisors, whose sum is σ = 168861662. Its totient is φ = 168861660.

The previous prime is 168861617. The next prime is 168861677. The reversal of 168861661 is 166168861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 114618436 + 54243225 = 10706^2 + 7365^2 .

It is an emirp because it is prime and its reverse (166168861) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 199198891 and 198891991.

It is a cyclic number.

It is not a de Polignac number, because 168861661 - 2⁹ = 168861149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (168861691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84430830 + 84430831.

It is an arithmetic number, because the mean of its divisors is an integer number (84430831).

Almost surely, 2^168861661 is an apocalyptic number.

It is an amenable number.

168861661 is a deficient number, since it is larger than the sum of its proper divisors (1).

168861661 is an equidigital number, since it uses as much as digits as its factorization.

168861661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 43.

The square root of 168861661 is about 12994.6781799320. The cubic root of 168861661 is about 552.7265831493.

The spelling of 168861661 in words is "one hundred sixty-eight million, eight hundred sixty-one thousand, six hundred sixty-one".