216971 has 4 divisors (see below), whose sum is σ = 229752. Its totient is φ = 204192.

The previous prime is 216967. The next prime is 216973. The reversal of 216971 is 179612.

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

It is a cyclic number.

It is not a de Polignac number, because 216971 - 2² = 216967 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 216971.

It is not an unprimeable number, because it can be changed into a prime (216973) 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, 6365 + ... + 6398.

It is an arithmetic number, because the mean of its divisors is an integer number (57438).

2²¹⁶⁹⁷¹ is an apocalyptic number.

216971 is a deficient number, since it is larger than the sum of its proper divisors (12781).

216971 is a wasteful number, since it uses less digits than its factorization.

216971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12780.

The product of its digits is 756, while the sum is 26.

The square root of 216971 is about 465.8014598517. The cubic root of 216971 is about 60.0897730205.

The spelling of 216971 in words is "two hundred sixteen thousand, nine hundred seventy-one".