216655 has 4 divisors (see below), whose sum is σ = 259992. Its totient is φ = 173320.

The previous prime is 216653. The next prime is 216661. The reversal of 216655 is 556612.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 216655 - 2¹ = 216653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21661 + ... + 21670.

It is an arithmetic number, because the mean of its divisors is an integer number (64998).

2²¹⁶⁶⁵⁵ is an apocalyptic number.

216655 is a deficient number, since it is larger than the sum of its proper divisors (43337).

216655 is an equidigital number, since it uses as much as digits as its factorization.

216655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43336.

The product of its digits is 1800, while the sum is 25.

The square root of 216655 is about 465.4621359466. The cubic root of 216655 is about 60.0605869479.

The spelling of 216655 in words is "two hundred sixteen thousand, six hundred fifty-five".