211381 has 8 divisors (see below), whose sum is σ = 225720. Its totient is φ = 197568.

The previous prime is 211373. The next prime is 211403. The reversal of 211381 is 183112.

It can be written as a sum of positive squares in 4 ways, for example, as 140625 + 70756 = 375^2 + 266^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 211381 - 2³ = 211373 is a prime.

It is a super-2 number, since 2×211381² = 89363854322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211681) 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 7 ways as a sum of consecutive naturals, for example, 975 + ... + 1171.

It is an arithmetic number, because the mean of its divisors is an integer number (28215).

2²¹¹³⁸¹ is an apocalyptic number.

It is an amenable number.

211381 is a deficient number, since it is larger than the sum of its proper divisors (14339).

211381 is a wasteful number, since it uses less digits than its factorization.

211381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263.

The product of its digits is 48, while the sum is 16.

The square root of 211381 is about 459.7618948978. The cubic root of 211381 is about 59.5692294958.

Adding to 211381 its reverse (183112), we get a palindrome (394493).

The spelling of 211381 in words is "two hundred eleven thousand, three hundred eighty-one".