218316481 has 2 divisors, whose sum is σ = 218316482. Its totient is φ = 218316480.

The previous prime is 218316443. The next prime is 218316491. The reversal of 218316481 is 184613812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 194463025 + 23853456 = 13945^2 + 4884^2 .

It is a cyclic number.

It is not a de Polignac number, because 218316481 - 2⁹ = 218315969 is a prime.

It is a super-2 number, since 2×218316481² = 95324171752446722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (218316491) 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, 109158240 + 109158241.

It is an arithmetic number, because the mean of its divisors is an integer number (109158241).

Almost surely, 2^218316481 is an apocalyptic number.

It is an amenable number.

218316481 is a deficient number, since it is larger than the sum of its proper divisors (1).

218316481 is an equidigital number, since it uses as much as digits as its factorization.

218316481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9216, while the sum is 34.

The square root of 218316481 is about 14775.5365723212. The cubic root of 218316481 is about 602.1372675872.

The spelling of 218316481 in words is "two hundred eighteen million, three hundred sixteen thousand, four hundred eighty-one".