216481 has 2 divisors, whose sum is σ = 216482. Its totient is φ = 216480.

The previous prime is 216451. The next prime is 216493. The reversal of 216481 is 184612.

216481 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., 216225 + 256 = 465^2 + 16^2 .

It is a cyclic number.

It is not a de Polignac number, because 216481 - 2¹¹ = 214433 is a prime.

It is a super-2 number, since 2×216481² = 93728046722, which contains 22 as substring.

It is a Chen prime.

It is a nialpdrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108240 + 108241.

It is an arithmetic number, because the mean of its divisors is an integer number (108241).

2²¹⁶⁴⁸¹ is an apocalyptic number.

It is an amenable number.

216481 is a deficient number, since it is larger than the sum of its proper divisors (1).

216481 is an equidigital number, since it uses as much as digits as its factorization.

216481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 384, while the sum is 22.

The square root of 216481 is about 465.2751873891. The cubic root of 216481 is about 60.0445040187.

The spelling of 216481 in words is "two hundred sixteen thousand, four hundred eighty-one".