218401 has 2 divisors, whose sum is σ = 218402. Its totient is φ = 218400.

The previous prime is 218389. The next prime is 218417. The reversal of 218401 is 104812.

It is a happy number.

It is an a-pointer prime, because the next prime (218417) can be obtained adding 218401 to its sum of digits (16).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 160801 + 57600 = 401^2 + 240^2 .

It is a cyclic number.

It is not a de Polignac number, because 218401 - 2¹³ = 210209 is a prime.

218401 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109200 + 109201.

It is an arithmetic number, because the mean of its divisors is an integer number (109201).

2²¹⁸⁴⁰¹ is an apocalyptic number.

It is an amenable number.

218401 is a deficient number, since it is larger than the sum of its proper divisors (1).

218401 is an equidigital number, since it uses as much as digits as its factorization.

218401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 218401 is about 467.3339277219. Note that the first 3 decimals coincide. The cubic root of 218401 is about 60.2214961330.

The spelling of 218401 in words is "two hundred eighteen thousand, four hundred one".