211391 has 4 divisors (see below), whose sum is σ = 213072. Its totient is φ = 209712.

The previous prime is 211373. The next prime is 211403. The reversal of 211391 is 193112.

It is a happy number.

211391 is nontrivially palindromic in base 14.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-211391 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 211391.

It is not an unprimeable number, because it can be changed into a prime (211291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 635 + ... + 908.

It is an arithmetic number, because the mean of its divisors is an integer number (53268).

2²¹¹³⁹¹ is an apocalyptic number.

211391 is a deficient number, since it is larger than the sum of its proper divisors (1681).

211391 is a wasteful number, since it uses less digits than its factorization.

211391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1680.

The product of its digits is 54, while the sum is 17.

The square root of 211391 is about 459.7727699636. The cubic root of 211391 is about 59.5701688468.

The spelling of 211391 in words is "two hundred eleven thousand, three hundred ninety-one".