218555231 has 2 divisors, whose sum is σ = 218555232. Its totient is φ = 218555230.

The previous prime is 218555209. The next prime is 218555257. The reversal of 218555231 is 132555812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 218555231 - 2⁶ = 218555167 is a prime.

It is a super-2 number, since 2×218555231² = 95532777994926722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218555261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109277615 + 109277616.

It is an arithmetic number, because the mean of its divisors is an integer number (109277616).

Almost surely, 2^218555231 is an apocalyptic number.

218555231 is a deficient number, since it is larger than the sum of its proper divisors (1).

218555231 is an equidigital number, since it uses as much as digits as its factorization.

218555231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12000, while the sum is 32.

The square root of 218555231 is about 14783.6135974937. The cubic root of 218555231 is about 602.3566858962.

The spelling of 218555231 in words is "two hundred eighteen million, five hundred fifty-five thousand, two hundred thirty-one".