218364581 has 2 divisors, whose sum is σ = 218364582. Its totient is φ = 218364580.

The previous prime is 218364569. The next prime is 218364583. The reversal of 218364581 is 185463812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 154604356 + 63760225 = 12434^2 + 7985^2 .

It is a cyclic number.

It is not a de Polignac number, because 218364581 - 2¹⁰ = 218363557 is a prime.

It is a super-2 number, since 2×218364581² = 95366180470611122, which contains 22 as substring.

Together with 218364583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218364583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109182290 + 109182291.

It is an arithmetic number, because the mean of its divisors is an integer number (109182291).

Almost surely, 2^218364581 is an apocalyptic number.

It is an amenable number.

218364581 is a deficient number, since it is larger than the sum of its proper divisors (1).

218364581 is an equidigital number, since it uses as much as digits as its factorization.

218364581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46080, while the sum is 38.

The square root of 218364581 is about 14777.1641731423. The cubic root of 218364581 is about 602.1814857725.

The spelling of 218364581 in words is "two hundred eighteen million, three hundred sixty-four thousand, five hundred eighty-one".