218426581 has 2 divisors, whose sum is σ = 218426582. Its totient is φ = 218426580.

The previous prime is 218426479. The next prime is 218426599. The reversal of 218426581 is 185624812.

218426581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 210395025 + 8031556 = 14505^2 + 2834^2 .

It is a cyclic number.

It is not a de Polignac number, because 218426581 - 2⁹ = 218426069 is a prime.

It is a super-2 number, since 2×218426581² = 95420342574699122, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 218426581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218726581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109213290 + 109213291.

It is an arithmetic number, because the mean of its divisors is an integer number (109213291).

Almost surely, 2^218426581 is an apocalyptic number.

It is an amenable number.

218426581 is a deficient number, since it is larger than the sum of its proper divisors (1).

218426581 is an equidigital number, since it uses as much as digits as its factorization.

218426581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30720, while the sum is 37.

The square root of 218426581 is about 14779.2618557220. The cubic root of 218426581 is about 602.2384726076.

The spelling of 218426581 in words is "two hundred eighteen million, four hundred twenty-six thousand, five hundred eighty-one".