216568181 has 2 divisors, whose sum is σ = 216568182. Its totient is φ = 216568180.

The previous prime is 216568171. The next prime is 216568193. The reversal of 216568181 is 181865612.

216568181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 214036900 + 2531281 = 14630^2 + 1591^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216568181 is a prime.

It is a super-2 number, since 2×216568181² = 93803554043297522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216568171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108284090 + 108284091.

It is an arithmetic number, because the mean of its divisors is an integer number (108284091).

Almost surely, 2^216568181 is an apocalyptic number.

It is an amenable number.

216568181 is a deficient number, since it is larger than the sum of its proper divisors (1).

216568181 is an equidigital number, since it uses as much as digits as its factorization.

216568181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23040, while the sum is 38.

The square root of 216568181 is about 14716.2556718752. The cubic root of 216568181 is about 600.5256329008.

The spelling of 216568181 in words is "two hundred sixteen million, five hundred sixty-eight thousand, one hundred eighty-one".