218551 has 2 divisors, whose sum is σ = 218552. Its totient is φ = 218550.

The previous prime is 218549. The next prime is 218579. The reversal of 218551 is 155812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 218551 - 2¹ = 218549 is a prime.

Together with 218549, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109275 + 109276.

It is an arithmetic number, because the mean of its divisors is an integer number (109276).

2²¹⁸⁵⁵¹ is an apocalyptic number.

218551 is a deficient number, since it is larger than the sum of its proper divisors (1).

218551 is an equidigital number, since it uses as much as digits as its factorization.

218551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 400, while the sum is 22.

The square root of 218551 is about 467.4943849930. The cubic root of 218551 is about 60.2352798873.

The spelling of 218551 in words is "two hundred eighteen thousand, five hundred fifty-one".