221381 has 4 divisors (see below), whose sum is σ = 225612. Its totient is φ = 217152.

The previous prime is 221327. The next prime is 221393. The reversal of 221381 is 183122.

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 184900 + 36481 = 430^2 + 191^2 .

It is a cyclic number.

It is not a de Polignac number, because 221381 - 2⁶ = 221317 is a prime.

It is a super-2 number, since 2×221381² = 98019094322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

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 221381.

It is not an unprimeable number, because it can be changed into a prime (221311) 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, 2036 + ... + 2141.

It is an arithmetic number, because the mean of its divisors is an integer number (56403).

2²²¹³⁸¹ is an apocalyptic number.

It is an amenable number.

221381 is a deficient number, since it is larger than the sum of its proper divisors (4231).

221381 is an equidigital number, since it uses as much as digits as its factorization.

221381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4230.

The product of its digits is 96, while the sum is 17.

The square root of 221381 is about 470.5114238783. The cubic root of 221381 is about 60.4941596712.

The spelling of 221381 in words is "two hundred twenty-one thousand, three hundred eighty-one".