211961 has 4 divisors (see below), whose sum is σ = 219300. Its totient is φ = 204624.

The previous prime is 211949. The next prime is 211969. The reversal of 211961 is 169112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 102400 + 109561 = 320^2 + 331^2 .

It is a de Polignac number, because none of the positive numbers 2^k-211961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (211969) 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, 3626 + ... + 3683.

It is an arithmetic number, because the mean of its divisors is an integer number (54825).

2²¹¹⁹⁶¹ is an apocalyptic number.

It is an amenable number.

211961 is a deficient number, since it is larger than the sum of its proper divisors (7339).

211961 is an equidigital number, since it uses as much as digits as its factorization.

211961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7338.

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

The square root of 211961 is about 460.3922240872. The cubic root of 211961 is about 59.6236629610.

Subtracting from 211961 its reverse (169112), we obtain a square (42849 = 207²).

The spelling of 211961 in words is "two hundred eleven thousand, nine hundred sixty-one".