216191 has 4 divisors (see below), whose sum is σ = 222072. Its totient is φ = 210312.

The previous prime is 216179. The next prime is 216211. The reversal of 216191 is 191612.

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 216191 - 2⁶ = 216127 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2885 + ... + 2958.

It is an arithmetic number, because the mean of its divisors is an integer number (55518).

2²¹⁶¹⁹¹ is an apocalyptic number.

216191 is a deficient number, since it is larger than the sum of its proper divisors (5881).

216191 is an equidigital number, since it uses as much as digits as its factorization.

216191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5880.

The product of its digits is 108, while the sum is 20.

The square root of 216191 is about 464.9634394229. The cubic root of 216191 is about 60.0176799750.

The spelling of 216191 in words is "two hundred sixteen thousand, one hundred ninety-one".