221345 has 4 divisors (see below), whose sum is σ = 265620. Its totient is φ = 177072.

The previous prime is 221327. The next prime is 221393. The reversal of 221345 is 543122.

221345 is nontrivially palindromic in base 13.

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 165649 + 55696 = 407^2 + 236^2 .

It is a cyclic number.

It is not a de Polignac number, because 221345 - 2⁶ = 221281 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22130 + ... + 22139.

It is an arithmetic number, because the mean of its divisors is an integer number (66405).

2²²¹³⁴⁵ is an apocalyptic number.

It is an amenable number.

221345 is a deficient number, since it is larger than the sum of its proper divisors (44275).

221345 is an equidigital number, since it uses as much as digits as its factorization.

221345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44274.

The product of its digits is 240, while the sum is 17.

The square root of 221345 is about 470.4731660786. The cubic root of 221345 is about 60.4908803958.

Adding to 221345 its reverse (543122), we get a palindrome (764467).

It can be divided in two parts, 221 and 345, that multiplied together give a triangular number (76245 = T₃₉₀).

The spelling of 221345 in words is "two hundred twenty-one thousand, three hundred forty-five".