168601781 has 2 divisors, whose sum is σ = 168601782. Its totient is φ = 168601780.

The previous prime is 168601759. The next prime is 168601789. The reversal of 168601781 is 187106861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 128482225 + 40119556 = 11335^2 + 6334^2 .

It is a cyclic number.

It is not a de Polignac number, because 168601781 - 2¹⁸ = 168339637 is a prime.

It is a super-2 number, since 2×168601781² = 56853121112743922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (168601789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84300890 + 84300891.

It is an arithmetic number, because the mean of its divisors is an integer number (84300891).

Almost surely, 2^168601781 is an apocalyptic number.

It is an amenable number.

168601781 is a deficient number, since it is larger than the sum of its proper divisors (1).

168601781 is an equidigital number, since it uses as much as digits as its factorization.

168601781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 38.

The square root of 168601781 is about 12984.6748515317. The cubic root of 168601781 is about 552.4428867479.

The spelling of 168601781 in words is "one hundred sixty-eight million, six hundred one thousand, seven hundred eighty-one".