216129 has 4 divisors (see below), whose sum is σ = 288176. Its totient is φ = 144084.

The previous prime is 216127. The next prime is 216133. The reversal of 216129 is 921612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 216129 - 2¹ = 216127 is a prime.

It is a D-number.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36019 + ... + 36024.

It is an arithmetic number, because the mean of its divisors is an integer number (72044).

2²¹⁶¹²⁹ is an apocalyptic number.

It is an amenable number.

216129 is a deficient number, since it is larger than the sum of its proper divisors (72047).

216129 is an equidigital number, since it uses as much as digits as its factorization.

216129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72046.

The product of its digits is 216, while the sum is 21.

The square root of 216129 is about 464.8967627334. The cubic root of 216129 is about 60.0119420674.

The spelling of 216129 in words is "two hundred sixteen thousand, one hundred twenty-nine".